Tuesday, 26 August 2008


Numbers based on the Cessna 152: At the Flying Training Organisation (F.T.O.) where I operate all take-offs and all approaches are SHORT FIELD techniques. It is not standard practice to make FLAPLESS APPROACHES except for training purposes and subject to the weather and wind conditions. The training is for Flap failure or electrical failure affecting the operation of the Flap motor.The main points to consider when planning a FLAPLESS APPROACH are: 1.) Increased ATTITUDE. 2.) Less DRAG. 3.) Less POWER required. 4.) Higher SPEED. 5.) Increased RATE of DESCENT. 6.) Lower DECELERATION. It IS necessary to think about the flapless approach BEFORE you commit, especially the FLARE.
Initially the Indicated Airspeed (IAS) on Base Leg should be the same as for a normal approach i.e. 65KIAS. In order to achieve this IAS, due to the lower drag, reduce the power to a lower setting than the normal 1500RPM datum. This reduced POWER should be around 1300RPM initially. LOOKOUT - ATTITUDE - INSTRUMENTS. It is important to maintain the height (QFE)/altitude(QNH), with progressively increasing attitude, until the IAS has decreased and is approaching 65KIAS. Now adjust the attitude to maintain 65KIAS in the descent. PROGRESSIVELY ADJUST the ATTITUDE & TRIM (P.A.A.T.). Turn onto FINAL Approach and, when lined-up with the runway centre-line, maintain the IAS at 60KIAS. As briefed in The Normal Circuit & Landing Ex 13, use Power (Throttle) to control Glide Path and Elevator to control Indicated Airspeed. BUT, as already stated, this is over-simplifying the technique and the controls and inputs should be coordinated to achieve the correct approach path at the correct speed. It is not appropriate here, to reiterate how to fly an approach whilst remaining aware of the effect of the wind direction and windspeed. Please refer to The Normal Circuit & Landing Ex 13 for a reminder of these techniques.
We are concerned here with the differences that a Flapless condition makes to the approach. You will notice that the ATTITUDE is very high on the approach. On more sophisticated aircraft, the correct action would be to raise the seat (electrically with a few blips on the seat switch) in order to see over the glare shield satisfactorily. This is not possible in an aircraft of this type, BUT be prepared for a changed "picture". As with all flying, make corrections small & early rather than large & late. This is even more important with a "slippery" low drag condition such as we have now. Deceleration to a lower IAS from the required 60KIAS will be slow, but acceleration to a higher IAS will be fast. So, as with all approaches, a high level of concentration is required. Make small power changes early. Early recognition of the need for a change in power or speed is the result of an effective LOOKOUT - ATTITUDE - INSTRUMENTS technique. Because the Groundspeed (GS) is higher than for a normal approach in the same conditions, the rate of descent (RoD) will also be higher.
The aircraft is approaching the threshold at a higher IAS and at a higher RoD with a poorer view of the runway. The threshold of the runway (TH) should be crossed at 60KIAS. It is important to get the aircraft down without delay. A conventional "flare" is not appropriate. Should the flare or roundout be too high, the aircraft is likely to float a long way down the runway due to low drag because of the clean wing. It is possible to run out of runway very quickly. If there is doubt about being in a position to touchdown at the right place, at the right speed then go-around. Therefore, as the aircraft approaches the surface of the runway at the touchdown zone (peripheral vision - you are looking out at the far end of the runway!) arrest the RoD for a firm (not hard, but positive) touchdown with a gentle back pressure on the control wheel. Use aerodynamic braking. Check the brakes early in the landing run. Lower the nosewheel of the aircraft when elevator authority is about to be lost.

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