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Takeoff incident

I had a rather unpleasant experience on takeoff from Visby (ESSV) last week.

The airport has a main runway 03/21. South of this runway there is a shorter grass runway 10/28. Further south is the aero club apron. The METAR about 1h45 before my departure was 21014KT CAVOK 25/12 Q1028. At the time of my departure the weather was much the same. Runway 21 was in use.

My 180 hp PA28 was parked at the aero club apron. The aircraft was loaded to within a few percent below MTOM. The tower offered me a choice of runway 21 or runway 10 with “a direct crosswind of 15 knots”. Using runway 21 would mean 3 km taxi, so I accepted runway 10.

I used flaps for takeoff and lifted the nosewheel at 49 knots (the POH figure). Immediately I was airborne I was in moderate turbulence, the airspeed dropped and a got stall warning. I lowered the nose and accelerated more or less in ground effect to a safe speed at which point I noticed the aircraft wouldn’t climb. I was rapidly running out of runway, but the aircraft was definitely flying (normal pitch attitude – not nose-high) and all engine indications were normal. Also there were no obstacles in the climb-out area so I decided to continue.

After carefully retracting flaps, I was rewarded with a 2-300 fpm climb (about 700 would be expected). When reaching 400’ AAL, I started a left turn that would take me on track (and also back to the airport if I things didn’t improve). Almost at once I was in a 1000 fpm climb, which after a while settled into a more normal rate.

My conclusion is that a thermal bubble had just released ahead and to the left of the runway. The air flowing to replace the bubble caused windshear and downdrafts. That would also account for the turbulence. When I turned, I flew through the rising air.

This was a very unpleasant experience and my passenger (wife, ex-PPL) was also not happy. The question is if I should (without the benefit of hindsight) have done anything differently. Clearly the safety margins were sufficient, but it was closer than I would have liked.

Last Edited by Airborne_Again at 07 Jul 11:02
ESKC (Uppsala/Sundbro), Sweden

Sorry to hear about your predicament. 20/20 hindsight is a wonderful thing, but does not alter what has gone by. 15kts, across runway 10, is getting to the upper reaches of certified crosswind components in a lot of GA. The PA28 is 17kts. You may find this https://assets.digital.cabinet-office.gov.uk/media/5422f4cded915d137400050b/Piper_PA-28-140_Cherokee__G-BOSR_02-09.pdf, of interest.

i would have taken the 3km taxi, and given myself the 15kts down runway heading, particularly if I were hot and heavy. You also used flaps, can we assume because runway 10 is shorter? CAVOK can also produce thermal activity, and if the runway is bordered by trees, than you may also encounter rotor. All these little things can add up to a bigger challenge, which you only find out about as you rotate. All good experience, you will know the next time..

Fly safe. I want this thing to land l...
EGPF Glasgow

Crosswinds are usually not a limit but “max demonstrated” and they apply to landing, not takeoff.

The 10/28 runway appears to be 1100mtrs of grass.

To be honest, I wouldn’t have had any concerns about that myself so long as I was sure the aircraft was within W&B, which you were. I too would have taken the grass runway (assuming the grass wasn’t very long).

There comes a point in any departure when it’s no longer possible to land back on the runway. As I see it, you used flaps as you wanted to get off the grass as soon as possible, and planned to accelerate in ground effect. I’d probably had made the same choice.

Apparently you did manage to accellerate in ground affect. I suspect that by the time you’d realised that you could’t climb, you were already beyond the “land back on the runway” point.

Given the circumstances, I think you did the only sensible thing which was to stay in ground effect as long as possible, continue to accelerate and retract flaps.

Good job I’d say!

EIWT Weston

Landing and takeoff…..

23.1585 Operating Procedures
(a) [ For all aeroplanes, information concerning normal, abnormal (if applicable), and emergency procedures and other pertinent information necessary for safe operation and the achievement of the scheduled performance must be furnished, including:
……………
(2) [ The maximum demonstrated values of crosswind for takeoff and landing, and procedures and information pertinent to operations in crosswinds;
…………..

Home runway, in central Ontario, Canada

15kts, across runway 10, is getting to the upper reaches of certified crosswind components in a lot of GA. The PA28 is 17kts.

I don’t think the crosswind as such was a factor, as I was tracking the runway centerline all the way until passing the departure end of the runway. I am, of course, aware of the 17 kt crosswind limitation and have flown in limiting crosswind before.

i would have taken the 3km taxi, and given myself the 15kts down runway heading, particularly if I were hot and heavy. You also used flaps, can we assume because runway 10 is shorter?

The main difference in using the main runway would have been more time before running out of runway. Runway 21 is about 2000 m. Runway 10 is 1100 m long and given the density altitude the necessary runway length according to the POH (with correction for grass) would be around 650 m. Strictly speaking, flaps wouldn’t have been necessary and considering the crosswind, it might have been better not to use flaps. OTOH, as I said, the crosswind in itself was not the problem.

CAVOK can also produce thermal activity, and if the runway is bordered by trees, than you may also encounter rotor.

Certainly I know that you can have thermal activity – I used to fly gliders – but that can always happen in sunny weather. No trees.

All these little things can add up to a bigger challenge, which you only find out about as you rotate.

Exactly! So my question remains. I think I did everything correctly once things started to go wrong, but would really have liked to not get into that situation in the first place.

All your suggestions are sensible, but taken to the letter they would mean that flying from a grass airfield with a short runway (such as the 630 m runway at my home airfield) shouldn’t be done when thermal activity is likely. After the fact, I was considering that too, but it does seem to me to be going a bit too far.

Last Edited by Airborne_Again at 07 Jul 12:23
ESKC (Uppsala/Sundbro), Sweden

achimha wrote:

Crosswinds are usually not a limit but “max demonstrated” and they apply to landing, not takeoff.

According to current Swedish regulations, “max demonstrated” is an operational limit. Not that the aircraft cares how the regulations are written, of course.

ESKC (Uppsala/Sundbro), Sweden

dublinpilot wrote:

As I see it, you used flaps as you wanted to get off the grass as soon as possible, and planned to accelerate in ground effect. I’d probably had made the same choice.

Apparently you did manage to accellerate in ground affect. I suspect that by the time you’d realised that you could’t climb, you were already beyond the “land back on the runway” point.

Actually, I would have expected to accelerate during the initial climb with flaps extended. This is normally no problem even when the aircraft is fully loaded. The density altitude in this case (≈1200 ft) wasn’t high enough to make a major difference.

ESKC (Uppsala/Sundbro), Sweden

The density altitude in this case (≈1200 ft) wasn’t high enough to make a major difference.

1200ft is nothing, really. Maybe a stupid question, but could it be that you inadvertently crossed the controls while taking care of the crosswind during takeoff? I’ve seen that a lot with students. The tiniest little bit of sideslip can ruin your climb, especially with flaps extended.

Personally I am no fan of grass runways and would have taxied any length to find some concrete for my wheels.

EDDS - Stuttgart

When you noticed the aircraft bogging down, did you have enough runway remaining to land again?

EGTK Oxford
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