Knowing our male or female partner is often a matter of trust, assumption and love. Knowing an aircraft partner is more a case of faith and understanding. I thought you might enjoy a sortie of an unpleasant nature with me on a day when that bond of faith between me and my aeroplane was stretched by circumstances that were not entirely in our control.
I planned out my intended flight in the briefing room as usual. Checked the weather, looked at the NOTAM’s (notices to Airmen) and filled out the log in preparation for the flight. I walked out to my charge, a Piper Cherokee of 1966 vintage, and checked the oil, fuel, tyres and other external items that we normally include in a check – aircraft looking good and standing level on the grass.
Firing up the engine went as normal – on this aircraft it usually required 2 attempts. Then a quick chat to the control tower to seek permission to taxi to the threshold of the active runway – this isn’t a commercial airliner at a major airport… in fact we’re at a grass strip in England. Clearance given, brakes off and a careful waggle of the controls as we taxi to ensure that all the linkages are working correctly. Also watching the gauges to ensure that there are no anomallies – low or high temperatures are a bad thing.
At the holding area all the checks are normal and having done the run-up I ask for permission to enter the runway for take-off. No other traffic to worry about, I get the all clear from the tower. So I roll the plane onto the runway and check the brakes, temperatures and pressures for the final time while selecting the correct take-off position for the flaps (1st stage on a Cherokee unless runway conditions or length suggest 2 stages). Lined up and ready to go…
I opened the throttle to full power and we started to rumble down the grass runway – Rev’s increasing, pressures good. Nice and straight on the runway. Looking good…
Ok – so there the dream ended – looking at the dials I suddenly registered that I had no airspeed! Looking out the window suggested otherwise. Approaching the centre of the runway the aircraft was already saying ‘lets go fly’ – I had just missed the fact that the airspeed indicator wasn’t working 😦
Big decision time… Do I shut the throttle and slam on the brakes halfway down a runway that slopes downhill from the mid point or do I have faith in what the aeroplane is telling me and take on the climb out to work out how to resolve the issue from up there? I went with my partner… keep the power on and climb out to join the circuit. The aircraft wanted to fly – seemed to be the right choice at the time.
Climb out in a general aviation aircraft is pretty straight forward – full throttle and sensible angles of bank. So, that part is easy. It’s the turn down wind to parallel the runway that gives time to assess what to do. Hitting the downwind leg at full throttle is not a good idea – it’s usually designed to be flown at close to or slightly below cruise speed. This is where knowing my partner really started to pay dividends – she’s a 1966 Cherokee and my experience of flying her as an individual (they aren’t all the same) suggested cruise revs of 2300 so I set that and trimmed the aircraft for level flight. At this point the airspeed indicator started to creep up to something close to our flying speed but it would have been fatal to trust it. More important to trust the feel of the aeroplane!
I turned base leg and adjusted the throttle to around 1800 revs to give a rate of descent that I hoped would be around right and hung out the normal 2 stages of flap. (17-1800 revs usually gives about the right rate of descent on this aircraft). At this point it became a case of ignore the usual instruments, concentrate on the view out of the window and adjust the revs to achieve a good angle of approach whilst feeling what the aircraft was telling me – any hint of a stall and I’d need to crack the power on pretty sharpish! The old girl did it exactly as I expected her to – we came over the runway threshold slightly high and a little fast but the touchdown was good and the brakes then had 3/4 of the runway to play with. She was an absolute Gem – looking after me by reacting to my requests everytime.
So what caused the airspeed indicator problem?… Some tiny wasps using the static vent as a nest. I didn’t need this bit of excitement but I’m glad I shared it with a Lady that I knew 🙂 We had many other adventures in the 500 or so hours that we flew together but none quite as fundamental as that one!
Lessons learnt? Check the fact that the airspeed is rising very early on the take-off run. It becomes natural to ignore it because it is one of the least likely things to go wrong but not knowing how fast your aircraft is flying can be fatal – especially if you are un-familiar with the aircraft.