It’s been pretty windy this month.
A low hours PPL visited the club to ask if we would be flying today. He thought not because it seemed a bit windy but wasn’t exactly sure of the limits. It afforded a discussion between us and another instructor not just about what limits to apply, but why.
The first thought is about crosswind because this tends to be the limiting factor. Our DTO manual states that for experienced pilots anything up to the published crosswind limit of the aircraft is acceptable. A quick look at the aircraft POH confirms this to be 17 knots. But this is a demonstrated crosswind – it’s not completely scientific and just happened to be the wind strength on the day that the flight test was flown. If it had been 20 knots that day (and successfully flown), then that would have been the figure in the book. Test flight programs are expensive, so manufacturers don’t want to prolong their duration just to add an knot or two to that figure. The hard limit is determined where the loss of rudder authority when applying full deflection doesn’t allow you to achieve directional control to land safely.
So if the wind forecast is for more than 17 knots crosswind, then the club wouldn’t authorise you to fly. Picking a destination with a more into wind runway might resolve that issue.
The second factor is total wind strength. During my Flight Instructor training, we had some pretty windy flights in their PA28. Their ATO manual stated a maximum wind limit of 35 knots and there were several occasions when it was above 30. Here the limit is related more to the stall speed of the aircraft – you can’t land if you can’t stop flying. That’s a definite problem for microlight and lighter aircraft which may have a stall speed of 35 knots or less. In stronger winds you can choose to land flapless in order to achieve a higher stall speed. Your groundspeed will be quite low so you won’t need much runway. A good rule of thumb for a low hours PPL might be half the stall speed – in the case of a PA28 22 knots with flap or 25 without. As a more experienced pilot, I’d be OK with a higher speed of up to 35 knots in a PA28 or 40 in my TB20.
Planning a shared currency flight
This particular conversation came to mind for a short currency trip in the TB20 that John and I agreed to share. I wanted to practice an instrument approach so we decided on Hawarden (near Liverpool). Strong wind warnings were in force, forecast 25 gusting 35 but it was straight down the runway at both airports.
In addition to the usual NOTAM, weather and chart planning, I phoned for PPR at Hawarden and confirmed that they could accommodate an instrument approach, booked out at Gloucester and also phoned to reserve a table for lunch.
On departure the aircraft really wanted to fly and it was no trouble lifting off, encountering mild turbulence immediately on climb out. At 2,000 feet it was much smoother and we gained speed from the tailwind. Visibility was good, and it was easy to spot and fly around the few CBs which would have been turbulence to get close to. I hand flew rather than using the autopilot – the TB20 is very stable when properly trimmed, and in turbulence the autopilot has a habit of turning itself off.
We spent some time leaning the engine and recording parameters – we fitted GAMI injectors last year and are still finalising our standard operating procedures for leaning. However I can see this is already saving considerable amounts of fuel and will pay for itself in no time.
We switched to Shrewsbury for a MATZ transit service and heard few others in the sky, then switched to Harwarden Approach and requested the vectored ILS. This was easily accommodated, with just a confirmation from me that this would be VFR flight within Liverpool controlled airspace. The strong wind must have made the vectoring more interesting for the controller, and we were positioned with an easy intercept then handed over to tower. Windchecks were given a couple of extra times which are helpful – 25 gusting 38. That is at ground level of course, and it would have been a bit stronger at altitude. Despite that, the approach was fairly stable and within limits with just a few corrections for glideslope probably down to differing windspeeds rather than pilot error.
Touchdown was fairly smooth except for a gust that kept me airborne a little longer than anticipated.
The marshaller was ready to wave us into position, and arranged to refuel while we went for lunch – what great service.
Lunch and an impressive sight
The Chocks Away cafe is a popular venue for lunch, and it had been worthwhile to phone ahead to reserve a table.
Prior to departure, we saw a Beluga transport aircraft taxying out. The turning circle is incredibly small because the nosewheel can be turned almost perpendicular. It made a graceful departure despite the strong headwind.
John flew us back and positioned for a straight in for runway 22, which with few other aircraft around was easy for ATC to accomodate.
It felt good to have blown a few cobwebs off my TB20 currency – it’s easy to get complacent after flying so much in PA28s and there are a few differences to bear in mind.
PIC today: 1:00
Total PIC: 1,982:55
Total time: 2,195:05