You’ll remember the training – in an EFATO (engine failure after take-off): pick a field ahead and never turn back. There are 5 compelling reasons for this
1. considerable height is lost in the turnback
2. there is the risk of stalling / spinning if you get too slow
3. you’ll be landing with a tailwind
4. in most case, a 180o turn does not position you in line with the runway. A further 90o turn is required, followed by a turn reversal
5. After all this, in all but the lightest winds and the largest airfields, you will have drifted downwind, leaving little runway left for the landing.
On my bi-annual last month in the Sportcruiser, we measured the height loss in a 180o turnback. Starting above 2000ft, from a full power Vy climb, we cut the power to idle, simultaneously pitching down for best glide speed and initiating and completing a 180o turn. We did this with take-off flap and flapless. We tested each at bank angles of 15o, 30o and 45o (with a 5 knot speed increase to compensate for the increased load factor).
With flap, the best result was a 30o bank turn which lost 200 ft. Flapless, the 15o turn lost least height (200 ft). All other configurations lost 300 to 350 feet. These results can probably be explained by 3 factors: the extra drag of flaps, the duration of the turn, and the increased load factor (and therefore drag) in steeper turns.
In a real engine failure, the height loss will be more – due to the ‘startle effect’ and inaccurate flying speed in the heat of the moment. Furthermore, if we fly on QNH, we are not as high above ground as a quick glance at the altimeter suggests. Also remember that other aircraft may perform less well: the Sportcruiser has a better glide ratio than many trainers.
To reiterate: turning back is not recommended if you are below circuit height. If you wish to see for yourself, only do so at a safe height, with an instructor on board.