Manoeuvring Speed Va

Manoeuvring Speed Va

Why should I read this? Because one of the commonest problems encountered by the pilot who loses control, perhaps after straying into IMC, is the spiral dive. Mishandle this and you may be parted from one of your wings (or gain another two)! Now read on…

As a follow up to the AA Flight 587 from New York, the Federal Aviation Administration (FAA) has produced a Special Airworthiness Information Bulletin (SAIB). This points out that the cause of separation of this airliner’s tail fin with the resultant death toll of 260, was the excessive rudder pedal inputs, even though the airspeed was below Va.

The SAIB points out that the design manoeuvring speed, Va, is the speed below which you can make a SINGLE FLIGHT CONTROL to its FULL DEFLECTION for ONE AXIS ONLY in smooth air.

Don’t forget that the Va is not the same as Vo, the smooth air maximum operating speed (the top of the green arc) though it may be close. In the PA28 Va is 111kts and Vo 126kts (but then, as a regular PA28 pilot you knew that anyway??) But note also that the Va figure quoted will be at maximum all up weight and the figure is much reduced at lighter weights. If you can’t work out why this apparent paradox occurs ask a friendly instructor!

Why am I inflicting this information on you? The commonest error I encounter when testing candidates or doing a dual flight, is that during the recovery from a spiral dive they input both roll and pitch controls at the same time when the speed is way above Va. This is dangerous and could lead to structural failure.

Hence, recovery from a spiral dive:

Close the throttle

Gently roll the wings level

Ease out of the dive

Assume climb attitude

Delay opening the throttle till the airspeed reduces to the normal cruising range.

If you haven’t done one for a bit, again, ask your friendly Flight Instructor.

Geoff Prout, C.F.I.