Mention 1.
Thanks for that post. Now that I find very interesting and will keep that in mind. What can happen is that during an asymmetric circuit with one engine set at zero thrust (usually about 11.5 MP in Seminole/Duchess types), the U/C horn sounds.
I have seen people then nudge that throttle up a tad to stop the horn from sounding. There goes one safety net.
Then on final some prefer to use minimum flap (for go-around capability) and unless the flaps are set beyond a certain setting, the gear horn will not sound either. There goes the second safety net.
If significant power is used on the live engine until the flare, the horn may not sound until into the flare.
Way back in the mists of time a DCA Avro 125 did a wheels up landing at Avalon with two DCA Examiners aboard . It was on a flapless, necessitating low thrust lever settings and the pilot silenced the horn late downwind. The thrust levers being almost at idle on base and final were such that the horn never re-armed. A very smooth belly landing resulted.
On another incident (well, almost), involving a practice asymmetric at Canberra in the first of the RAAF's Avro 748's, a wheels up landing was averted by the alert QFI (takes modest bow and awaits tumultuous applause in Pprune pages).
The 748 had the usual horn warnings attached to the throttles and flap positions. But it also had a dinky little device in the face of the ASI. If the aircraft got below a certain speed on final with gear still up, the word U/C displayed itself and flashed. You could never miss it. Never?? Don't you believe it. The student undergoing endorsement training was downwind with one on zero thrust (Rolls Royce Dart engine). Student distracted by noise of horn and pushes horn silence button. Delete first safety net.
Told to extend downwind due someone else long final, therefore delays lowering of gear. Good thinking 99. Eventually turns base and starts descent but with plenty of power on live engine due long way out.
Forgets to call for gear. QFI twigs to this and keeps eye on things. Eventually student calls for landing flap and off goes the horn real loud. Student concentrating on glide path and ignores (or never hears) horn. QFI now wide awake and watching with great interest the unfolding drama.
At 600 ft on final with gear up, full flap and around 100 knots, the ASI U/C warning flag starts to flash urgently (the one that you can't miss!). Student looks right through it as he tries to pin the airspeed. QFI now watching a life lesson in how a pilot can somehow be concentrating so much that he misses all the obvious signs of a potential gear up landing.
Finally QFI orders a go-around on both engines (easy enough because one was set at zero thrust and not feathered). Student opens up power and calls for gear up. QFI tells him to pull his own gear up. Student reaches across to gear lever and is dumbfounded to see the gear lever is already up.
I would never have believed this could have happened given the various safety nets for gear operation in the 748. But it did.
Interesting too, is the common flying school dogma of teaching ab-initio students to call Undercarriage Down and Locked in fixed gear aircraft on the premise that one day the student will go on to a retractable and that it is a Good Thing - even though it does not apply to a fixed gear Cessna/Warrior - nor is it called for in the manufacturer's POH. This policy is yet another of the myths taught in GA. Interesting too, that the RAAF do not teach the mythical gear down policy in their earlier CT4 trainers but wait until their trainee pilots go on to the PC9 retractable.
My understanding is that the retractable gear aircraft is a specific rating and that is where the student should be taught the new extra check of gear position and not before. One can speculate how many of those who have had the unfortunate experience of forgetting to lower their wheels were earlier taught the superfluous Gear Down check during their ab-initio training on fixed gear aircraft.
