It is a year since I passed my initial flight test for my PPL. According to South African air law, after one year, you need to revalidate your PPL (and thereafter every two years). This is done via a ground briefing/exam and a flight test.
In the year since I got my PPL I have flown about 70 hours, 11 of that as dual instruction for my night rating and 5 odd hours in the sim. The rest, apart from a few jaunts in the SR20 with family, has been in my Sling 4 ZU-IBM. There have been a lot of local flights – practicing stuff, keeping current and proficient, and the odd long trip – most memorable being the flight to Cape Town and back in November last year, with a few family day trips thrown in here and there.
May and June are busy months from a flying admin point of view. My medical (which needs to be done annually) expires at the end of May. My PPL needs to be renewed by the end of June. This makes this a busy couple of weeks.
To renew my medical requires an annual audiogram, lipogram and eye test. To be honest, I can’t see why these need to be done yearly (perhaps with the exception of the eye test?). Having to go through a medical every year at my age (42) seems superfluous – especially since I know I’m in good health.
It’s a public holiday – Worker’s Day and those of us who work are restless to get some air between us and the ground. There is some discussion in the club WhatsApp group about a suitable location for breakfast – some guys want to go to Thabazimbi for the NGK Meifees (May fest) but many of us are a little twitchy about flying to a town airfield and leaving our aircraft there, being transported to the festival ground and having to rely on folk to bring us back to the planes again.
I was supposed to fly to Middelburg(FAMB) this afternoon to camp at the AeroClub of SA Airweek being held there this weekend. The weather, it seems, had other ideas.
I was delayed by 30min at work this morning and by the time I arrived at the airfield the storm line was developing. I hung around finding things to do on the plane until 16h00 local by which stage I could probably have found a route but the flying time would have meant an after dark arrival – and I’m not night current at the moment – not landing at an unfamiliar field at night thank you very much.
All good things must come to an end and this includes congresses – well, OK, being at a congress (even one dedicated to anaesthetising small people) is not as good as not being at a congress when in Cape Town, but it was still worthwhile.
There was a huge amount going on from a social point of view but was able to have dinner with an old friend and her family and also to have the most expensive cocktails I have ever drunk – I know it’s Cape Town but R130 for a Mojito is somewhat excessive – it is one of the trendiest spots in town though and the views and architecture made up for the cost of the drinks (almost!)
I’d deliberately left an extra day to get back – my plan was, if the weather looked at all dubious on the Monday, I’d aim to fly halfway back on Sunday afternoon, use the night rating to land late in Bloemfontein and sleep over and hop home on the Monday. My weather guy seemed confident that weather would be excellent on the Monday – with the proviso I left early ( 0600 local). This seemed to me like an excellent plan – despite the logistical problems of accessing the airfield at that time (beyond the scope of this piece).
I was surprised to wake up to a thin layer of cloud, which got thicker as I descended down from Rondebosch to the peninsula and headed north to Morningstar. The logistical issues of accessing the airfield at 06h00 were left by the wayside as conditions were low IMC with 1000m visibility but, annoyingly the clouds would break up every few minutes to reveal that the layer was temptingly thin. I could feel the get-home-itis starting to build. It would be very easy to blast through a hole in the clouds, but what if I needed to return? I doubted I’d be able to find the field again, so in consultation with the weather briefer we decided to wait 2hours. This allowed ample time for a very thorough preflight, at least 2 pre departure visits to the bathroom and sorting out returning the hired car to the AMO/FBO.
At 8h30 there was much more blue sky than low cloud and I decided the time was now. I taxied out, did my run up and launched off of 02. Climbing through 300ft the EGTs all climbed rapidly through 1100deg – well into the red. It took me about 3 seconds to decide that I was not continuing with this – reported returning to the circuit and got IBM onto the ground as soon and as safely as I could – I will confess that my circuit was not textbook but I was keeping it tight in case the engine quit. Bizarrely the power output felt ok and there was no roughness at all.
I had the AMO check it out – they ground ran it, and then we test flew the plane again – we were unable to replicate the problem. A possible theory was carburettor icing (there is no carb heat on the Sling and conditions were favourable for development of carb ice) but there was no discernible power loss so I’m sceptical of that. Another theory is that I didn’t put the mags completely back to BOTH but again, I don’t believe this and once again no issue with power. So I’m at a loss as to what happened, but there have been no abnormal indications since then.
Date of Flight
12 November 2018
Morningstar to FATA(Tedderfield)
The nett result of all of this is that it was 10h15 local when I departed, a good 4 hours later than I had wanted. I was hoping for a smoother ride than coming down but was to be disappointed. Initially the air was fantastic and I was settling in for an easy trip but as I approached Sutherland the thermal activity started with a vengeance, as it had on the trip down. I climbed to FL95, where the density altitude was 12750ft – I didn’t believe I could justify a climb to FL115 without supplemental oxygen, so I was properly stuck.
It may be something I need to get used to and there may well be a technique to riding the thermals to get maximum efficiency. I think it may be easier in an aircraft that cruises below Va – the Sling will easily cruise in the yellow band – I was having episodes where I was 5-7.5deg nose down, climbing at 700fpm and rapidly approaching Vne, so I would pull throttle to idle, ride out the thermal and then try to time reapplication of throttle to not end up on the back side of the power curve – occasionally I needed to put the prop into climb and once had to put the throttle though the ‘gate’ to 115% power to not sink. This suggested to me that I was not only contending with updrafts but downdrafts as well.
This continued for the rest of the trip – to say it was tiring is an understatement. I was again fortunate to be cleared through the Kimberly (FAKM) TMA which cut about 30miles off the trip. Most worryingly for me and the primary reason why I chose not to stop and take a break was the possibility of thunderstorm development. I was overhead Kimberley at about 13h45 local and had planned to already be in my car driving home from the airport by that stage.
Looking at the radar download I could see that there were some cells starting up so I elected to continue. Approaching Potchefstroom there were definitely cells but they were isolated so was able to manoeuvre my way around them – it is so tempting to fly underneath them but there was a lot of Virga about and I know well that that implies severe downdrafts – best avoided. So we picked our way through the cells. Typically I was unable to raise any cell signal to download the current radar pictures – man I wish we had a decent ADS-B in solution provided here. ATC was fairly noncommittal, “yes there are some buildups but they don’t look too hectic” – easy to say sitting in a comfortable chair.
Finally I was able to call overhead Tedderfield – had a bit of a fiddly landing as the gusts were starting up prior to a storm arriving but safely down and then the big job of unloading the aircraft.
5.9hours in a single leg is a long flight – it would have been better with less turbulence. I learned some important lessons though – leave as early as possible if possible, and rather leave a day earlier if there is any doubt about the weather. If I was to do this trip again (I’m sure I will), I will land at Cape Town international (FACT), suck up the higher landing fees and then be able to (a) access the aircraft whenever needed and (b) be able to depart before sunrise (Morningstar has no airfield lighting).
For a first long cross country trip I think it went really well. It had moments of frustration and times when I was quite anxious about the effects of the turbulence on continued flight. But that feeling when your destination comes into view after a long trip and you know you’ve made it? It’s fantastic.
So I have a new type on my license – and some endorsements to go with it! I recently spent two days at Wonderboom Airport (FAWB) getting rated on the Sling 2.
The Sling is a locally (South African) designed and built aircraft. It’s nominally a light sport aircraft but as configured it requires a PPL to fly as the maximum takeoff weight is over 600kg. Interestingly the same aircraft, with one wing tank removed will have a MTOW < 600kg and can be flown on a recreational pilot license as a light sport airplane.
It’s also quite different from the Cirrus I have done all my training on to date. Of course, it’s much lighter, all metal and has a significantly different engine? How different? Well, it’s a Rotax 914 – a 1.2l 4 cylinder producing 115hp compared to the Continental 0-360 6 banger on the Cirrus. It’s also turbocharged and the prop is a variable pitch constant speed unit (Yes, the Cirrus had a variable speed CSU but with no direct pilot control). Importantly, it burns MUCH less fuel – 20litres per hour compared to the 50-65litres per hour on the Cirrus. And it will burn MoGas happily too.
To obtain the conversion onto the Sling was not an easy matter. Firstly, there are a lot of flight schools operating Sling 2s. There are only 2 in the country that have the Sling 2 914 Turbo on their ATO. Thus I had to travel to Wonderboom, which is a great airport. Unfortunately it is 90km from my house. Not so good. I did the conversion through FliteCare who were fantastic – they could accommodate me at short notice, and their desk staff were amazing.
I first needed to have briefings on the Sling aircraft itself – concentrating on the many differences between it and the Cirrus – this took about an hour, then it was time to dive into the nitty gritty of turbochargers and variable pitch propellers. Turbochargers are easy to understand – once you figure out how the wastegate works and the differences between the hot and cold sections. The variable pitch propeller on the other hand I found to be a lot more complicated. It’s bloody brilliant engineering but seems very complex. My biggest problem is remembering the difference between fine and coarse pitch which I find counterintuitive.
As it turns out, the intricacies of the variable pitch prop are moot in the Sling because it has a very clever system to adjust prop pitch. Firstly, instead of being controlled by oil pressure and springs, the pitch is adjusted electrically by servos in the hub. And there is no pitch lever as would be suspected, but a pitch control instrument on the panel which has a knob to select T/O, Climb, cruise, hold, and Feather. One can also bypass the selector and adjust pitch manually should the control unit fail – this is done with a rocker switch. Once a setting is selected, the CSU adjusts pitch to maintain the required RPM on the prop. Because the Rotax is a geared engine, engine RPM does not directly reflect prop RPM – so prop rpm is not set, but the CSU will indirectly control engine RPM.
Speaking about engine RPM – this is high! A regular aviation mill will turn at about 2500-2700RPM. The Rotax idles at 2000 and will go all day at 5500. An interesting feature about the 914 is that full power is actually 100hp with an additional 15hp available when you push the throttle through the gate – allows 115hp for up to 5min – would primarily be used for takeoff and initial climb to 300ft AGL and obviously for the go-around. In the gate position the engine is turning at 5800rpm.
After the briefings, it was time to fly. The conversion requires upper air work, simulated engine failure and at least 5 landings. Preflight is fairly standard with the addition of a prop control unit check – cycle from full fine to coarse with the engine off (remember those electric servos?). The other very different aspect is the dry sump oil system – oil is stored in the oil tank – so in order to check the oil one needs to ensure all the oil is in the tank and not in the crankcase. This involves turning the prop by hand (check mags off, key out master off first!) until the telltale gurgle from the tank indicates that the oil has returned.
Dragging the plane out of the hangar is a one man affair – really a pleasure. Startup is a non event – fuel pumps on, fuel on and crank. It literally starts like a car engine. Run at 2000 until oil pressure settles then warmup is at 2500 until oil temp reaches 50C. Operating temps are much lower than conventional engine due to the hybrid air/water cooling system.
Taxiing is much simpler than the Cirrus due to the direct nosewheel steering – so much nicer than the free castoring nosewheel. She’ll roll 2 up at 2500 so the engine can warm nicely en route to the run up bay. Most pre takeoff checks are done on the taxi as they have a reputation of getting quite hot while idling stationary. In the bay it’s final checks, run up at 4000RPM checking the mags (<300drop and <115between), takeoff briefing and then it’s time to fly.
The best word to describe takeoff is “sporty”. Stabilise at 5500RPM and 100hp then through the gate to 115/5800. Lots of right rudder is required and before you know it, we’re at 48kts and the rotate call. Liftoff at 55kts and best rate at 75 has her climbing away comfortably at about 1200fpm. After takeoff checklist includes setting prop to climb, coming back out through the gate and cleaning up the flaps.
For the conversion we set off to the general flying area – steep turns are a non event – very easy to keep the nose up. Stalls are reasonably benign but I did detect a slight tendency to drop the wing and not a huge amount of buffet. The (brilliant) MGL Avionics iEFIS unit has an AOA indicator too which is helpful.
Then we did some circuits at Freeway airfield – which has a massive runway which is gravel. Also a non event for the Sling. I may think twice about taking an aircraft I owned onto a gravel strip but certainly it wasn’t an issue on this plane.
Back to Wonderboom with me having no idea at all of where I was – fortunately the instructor was at home in the airspace. The plan was to do a couple of circuits, but this was foiled by a medium sized Cb cell which decided to discharge itself over the airfield. Conditions on landing were challenging to say the least – significant wind shear and gusts from about 15degrees off the front of up to 25kts. The Sling handled this with admirable aplomb.
Sadly this meant I had to make the pilgrimage to FAWB again to finish the rating. We banged off 4 circuits easily in the mid morning this week – 2 normal landings (Flap 20), 1 flaps up landing (would really rather not do those….) and 1 short field stop and go. The procedure for landing the Sling is similar i believe to the C172 – cut power just short of the threshold and glide it in. You can’t do that in a Cirrus.. The short field landing we did just to demonstrate it – in the POH it says “short field landings as per normal landing” since the landing distance is about 270m. However, we did a short field approach – flaps 30 and standard piloting, stopped on the runway, and then did max performance short field takeoff – full throttle, brakes off, through the gate and full back pressure on the stick from the moment rolling starts. The nose wheel lifted of at 20kts and we broke contact at 48kts. Lower nose to Vx (75) and then up and away. Very impressive, especially when you look at the airport diagram and see how short the distance was – we landed on 29.
It’s really nice to have excess power available. So I’m now rated on the Sling2 and have endorsements for turbocharged engines and variable pitch propellers. Onward and upward!
Some of the best video I’ve seen on YouTube of flying is in the evening – after the sun has set. Being able to fly at night obviously extends the useful flying day and also improves the options for waiting out weather and other potential delays. I’m a firm believer in having options to decrease the risk of acute get-there-itis.
With this in mind I’m setting off on my first post-PPL rating – the night rating. Interestingly we have the night rating as a separate rating instead of built into the PPL like it is in the United States. The requirements are not onerous but definitely stipulate dedicated experience in the dark – at least 3 circuits at night (I’ll be doing many more), 10 hours of instrument training (5 of which can be in the sim), a 150nm cross country by night and a theoretical exam.
As it stands currently, I’ve done 7 odd hours in the sim – all hard IFR flying and have enjoyed it quite a lot – I’m sure it’s the wasted youth playing Microsoft Flight simulator but at least I have some theoretical knowledge to hang onto that experience. So it’s actual night time flying I need – and this is what I did last night…
Date of Flight
19 July 2018
FALA(Lanseria, Johannesburg) - FALA
So. Flying at night. It’s… well…. dark. In fact this surprised me because I was anticipating that the lights on the plane would be better than they are. They’re not great for taxiing on the apron so that took a little getting used to. The lighting on the taxiways at Lanseria is great so that wasn’t an issue. No delays fro other aircraft on the field while taxiing which is always a plus. Run up and pre departure checks were as per normal, although I chuckled at my instructor when she said that we’d aim for the darkest patch off the end of the runway if we lost and engine, we’d turn on the landing light, and if we didn’t like what we saw we’d turn it off again. This did bring home the stark reality of night flying – it’s really difficult to find a safe landing spot should the big fan in front decide to stop. Lining up on 07 you get the sense of how dark it is – a row of lights leading out into almost infinity and just blackness beyond – not a sliver of moon in sight even.
Performance in ZS-ZIP was pleasantly surprising – 9 celsius outside temp will do that and climb out was brisk (for an SR20). The instructor had me on the gauges almost immediately after takeoff and I flew the numbers – 5deg nose up with 50% flaps at full power gave me just over 85kts (Vy) so we were at CAPS height crossing the 25 threshold which was reassuring. Then it was head down in the cockpit. The aim of the flight was instrument navigation introduction – I’ve done lots of sim time but this felt somewhat easier I thought. We did a number of VOR radial intercepts under the Lanseria TMA – I must say that the VOR intercepts are reasonably easy with it being a command instrument – fly to the needle and the only tricky bit is remembering which reciprocal to use (FROM top TO bottom). Then we climbed out into the practice area for some upper air work – clean and configured stalls (no problem) and some steep turns – again not an issue which is quite funny considering how much difficulty I had with them prior to my PPL practical test.
Then some timed turns which are challenging – essentially we work out an angle of bank for the rate one turn (TAS divided by 10 plus 6-7kts) which at 130kts TAS works out to be around 20deg. Then set up on a radial, bank in to the rate one bank angle, start the timer and then try and maintain 45deg of heading change every 15seconds – 3 deg per second. Not quite as easy as it sounds but very rewarding to get right. These will be useful later in IF training when it comes to holding patterns and procedure turns. Then it was time for some ADF work. ADF navigation puzzles me from a number of aspects. Firstly, it’s a big drain on my brain to figure out which way to turn each time and secondly, they’re essentially obsolete. They’re so obsolete, in fact that our 2004 model SR20 G2 has no ADF radio on board. As a result, we have to bodge an ADF navigation exercise by using the bearing needle on the HSI to point to a GPS location and then fly using that as an ADF station. It gets the job done and perhaps it’s ADF as ADF should have been.
Still, ADF intercepts are fiddly. Intellectually I know it’s a simple case of remembering where one is in relation to the station and turning appropriately. The little tricks – turning away from the desired QDM inbound and towards and beyond QDR for the outbound – do help, but they’re not intuitive – I’m guessing that practice practice practice will be the key to successful ADF navigation. Finishing up with some unusual attitude recovery (again, fun…) I considered we’d done some good work. So what is it like flying at night? I found it really serene – its you and the plane – I didn’t hear any nighttime rough running and the air was smooth (and freezing – note to self – take a better jersey next time) and calm. The lights stretch for miles and the dark patches do feel like they’re reaching up to grab you – I assumed all the dark patches are mountains because why would anyone put lights on a mountain? The best part for me is that the feeling is getting better – i.e I’m flying more by the seat of my pants than I have been before and it feels smoother – I do need to be a little bit less aggressive on my turns – I do tend to roll quite positively which works during the day but perhaps not as well under instrument conditions!
We decided we were chilled enough and headed back for Lanseria. One scheduled 737 on long final and then we were to roll in onto approach. The night time approach is easier, and harder than I thought. Flying the profile is easier than during the day as less gusts and updrafts but the roundout and landing was very different. The instructor was following me on the controls – we went over the threshold at what I felt was the right height having had 2 red and 2 white on the PAPI the whole way down. Then she says “do you feel like you’re sitting on the runway?” and I say, “Um… yes?” and she says, “OK, go to idle” and we touch down light as a feather – best landing ever I think. Which would be awesome, except in my mind we were about 5feet higher and I wasn’t expecting the touchdown at that point. This confused me a little as I was convinced that one would feel lower coming in at night. There is no centreline marking on the runway so the only visual reference is the side lighting – guess I need to pay more attention to that in the coming flights – which should be two sessions of night circuits. Can’t wait.
How do you make having a pilot license feel real? Fly with those who are most precious to you. For just over a year now I’ve been disappearing off to the airport for protracted periods of time and bringing nothing back other than stories of where I’ve flown, or how bad or good the conditions were or which exam I passed. I think it’s been a little hard on the family to be contributing (by managing without me at the house) but not getting any significant return.
So it was that after gaining my PPL (ok, long before even) there was significant interest from the family in going flying with me. There was much discussion, argument even about who would be first. “But Mike,” I hear you say, “You trained in a four seat aeroplane! Why can’t you take your wife AND two kids?”
Ah. And therein the rub. Most 4 seat aircraft are only nominally 4 seat aircraft on the South African highveld plateau. My home airfield has an altitude of 4500ft. ISA temperature for 4500ft is 6degrees Celsius. Only in the very depths of winter, when a cold front is passing, does the daytime temperature even approximate 6deg. So we’re by definition hot and high which degrades takeoff performance of normally aspirated aircraft – especially those with only 200hp on tap. Given that the flight school almost universally runs the aircraft with full/nearly full tanks, we are almost always payload limited in the SR20. The 22, on the other hand, with 310hp… not so much. (Which is why the only SR20s in South Africa are the 5 owned by the flight school. All the others are SR22s)
So, it would be that my wife and daughter would be first to fly with me. I hummed and hah’d about the routing. I wanted to do the city tour but decided to stick with what I know and simply cruise up and down in the flying training area. This turned out to be a very good call – as I was SO nervous that additional navigational demands would have seriously impacted my ability to fly safely. It gets real very quickly when your family is on the aircraft.
So how did it go? It was….. OK. The flying was good, the GF was quiet and I even threw in a steep turn to make sure everyone was awake. I gave the lecture (pre departure) on not talking while I’m on the radio and to let me know if they see any other aircraft – my daughter saw lots – I want her as my copilot – I’ll call her “Eagle Eye” from now on. The only downside was that it was pretty bumpy with the wind from the south rising up over the ridges and causing a little bit of turbulence. Landing was within spec (I thought it was pretty poor but the passengers thought it was ok) and just like that… I’d taken my first passengers for a plane ride.
More importantly, they both say they’ll fly with me again. This is the best part – because what is the use of the PPL if you aren’t going to use it to take people places? My little girl did get a headache which I put down to an uncomfortable headset (loaner) and possibly also being in the back seat without a cushion – note to self – remember the cushion next time.
My wife seemed surprised at how methodically I did my preflight and that I kept checking and double checking everything – I like to think I’m very cautious – this is what I normally do! I believe that I inspired confidence in her.
Date of Flight
7 July 2018
FALA(Lanseria, Johannesburg) - FARG(Full stop) - FALA
The second flight en famille was this last weekend – I took my mother-in-law and my son up. This would be a lot less pressured as I’d broken the back of my nervousness to carry passengers. I wanted to do some short field work so I took them out to my usual hunting ground Rustenberg(FARG) for a landing – it also gave them a chance to change seats – my MIL did the right seat out and my son back.
So FARG was extremely busy. I’ve never seen it like that before. When I called 10nm out there were 3 aircraft already in the pattern (one orbiting to drop parachutists) and 2 others inbound – which is a lot for an uncontrolled airfield. We’ve been suffering under a heavy high pressure system for a few days now – the QNH was 1038mmHg (30.65in) and I forgot to set to local until well into the descent which left me a little lower than I wanted to be for the overhead join but fortunately I was at the front of the queue and was able to recover on the downwind leg. Schoolboy errors..
The landing was (as should be at a shortish field) positive and we taxied onto the apron for the seat swap. As I’m taxiing out to 16, the paradrop guy announces he’s commenced his meat bombing run – so I ask him how many jumpers – 8 or 9 he replies…. OK. Then I ask where they are because I can’t see them from the hold short position and his response is to say “Don’t worry, you’re well away from them – just go you’ll be ok.”
Hmm. Didn’t seem like the best advice but after checking again to see they were not on the upwind and as I was departing straight out I decided to go for it. Didn’t see them at all. I even looked back after takeoff and didn’t see them. Oh well. I’d have been much happier to have eyes on but since the drop pilot didn’t even know how many jumpers he had, it seems like it wouldn’t have been that helpful to have seen some. I’d be interested to know what the procedures are at other fields where skydiving occurs. To me the safest approach would be to halt all ops until the divers are all recovered onto the field but I’m not that keen on sitting there with the Hobbs running while people drift down 4000ft under canopies.
But back to Lanseria we went only to find that every man and his dog was, in fact flying today. We were 4th inbound to the left downwind with a B737 on long final and 2 on the right downwind – Orbits, orbits for everyone! But the best part (after having to fly a 7mile final) was that the wind was blowing directly down the runway. I think this is only the second time in my flying career and we made an absolute greaser. Top tip – when flying with your mother in law, make every landing a greaser. Another 1,5h in the logbook and cross country time to boot.
I want to do my PPL(Instrument) so I need to log the cross country hours. Also starting the night rating so doing some sim hours too. The best part is that on reflection I don’t remember having to work too hard to fly the plane this time. Maybe I’m getting that feel – finally.
There is something about flying yourself for the first time with a freshly minted PPL certificate. No instructor to sign you out. Nobody double checking the tanks and the oil to make sure that you’ve put the caps back properly. It’s weird. But in a good way. I decided that I wanted to practice my landings and circuits mainly to keep current and proficient. Well. This was a lesson to me. This was going to be one of the worst flights I’ve ever done. 5 circuits. 2 reasonable landings. 2 balked landings (one from a PIO which got very scary very quickly – fortunately I remembered Thomas Turner’s One-Bounce-Rule and quickly got on the power and was away). The second balked landing was the scary one. I had a big bounce and wasn’t about to try my luck again – Full throttle but she just wouldn’t climb – so I ended up floating about 50ft above the runway for a while until airpseed built – in retrospect I should have triued to recover the landing with a bit less power to level off and give it another go – it’s a 10,000ft runway so there is almost always a chance to correct the landing – although this feels like cheating becasue not all runways are 10,000ft long!
So I left the field somewhat demoralised but have thought about it a lot and played through the scenarios in my head. I know what was wrong (poor airspeed control) and this is fixable – and to be honest the conditions were lousy – significant turbulence and variable winds on the final approach made nailing the airpseed somewhat tricky. Next week is another week – and it’ll be the first flight with my wife and daughter.