Originally Posted by
CVividasku
I'm not so sure about that, however quick decision is key.
It also depends on speed at this altitude.
You do not need to perform a 360° (In total) turn. Actually a 180° and a bit more will be enough.
The optimal bank angle for that turn is 45° theoretically, but 37° would be more sensible given considerations about getting the correct speed (higher at 45° bank).
Given a 2000fpm rate of descent during the turn and 1700 after, at 37° the half turn should take a bit less than one minute, so you would end up at around 1500ft in front of the runway. Getting able to get there will depend on energy management, airplane performance during the climb, and wind.
Assuming no wind, an average of 10% (6° climb), you would be at 5-6nm at the beginning and end of the turn. At 3° descent rate you would be well aligned for the runway.
However it may be very difficult to guess at the first time when to get the gear and flaps out.
My guess would be flaps 1 as soon as possible, flaps 2 if landing is assured, or delay the flaps 2 if a bit low.
Gear down would be very difficult to time as well, because it may be the emergency gravity procedure. But my guess would be 30s before landing especially if a bit low on energy. Then, using F3/Full to convert speed into altitude if required. May also be used to reduce vertical descent.
Then, if flaring from 1700fpm, flare should begin at approx 100ft and at least 10-15kt higher than the VLS.
With the APU started it may be much easier to do (availability of hydraulics mainly, but also some computers)
Feasible, but on a complex aircraft like this I would be a bit worried about the likeliness of success..
On a light aircraft I've done this procedure without a problem in real conditions. The only problem is to convince the controller to do such an unconventional exercise.
The best option to manage such an approach would be to be very high on the profile. Use F1/gear down to aim for the runway an even speedbrakes if required. Being able to retract the speedbrakes gives the possibility to go back up on the descent profile.
Then, the most important thing about flaring the aircraft is to understand that for same flare intensity, if the vertical descent rate is x times higher, the flare height should be x^2 times higher. I use this technique successfully every time I perform a landing on a 4° slope. Flare height is almost double. Being this early also ensures more time to notice unsatisfactory flare and use higher than normal intensity if required. However for very large vertical speed differences, speed decay during flare becomes sensible and must be taken into account. Hence the 10-15kt which is a guess on my part for 1700fpm.
There is a physics computation that I did, for 1kt of speed trend at 150kt, you will have 75fpm. So to cancel 1700fpm, you will see a 22kt speed trend on the PFD. Flare will last for about 6 seconds so 13 kt lost. My guess was not too far off !
Sorry! But failure at lower level is more of quick decision and visual judgment. Many things you assumed are not correct. APU won't give you hydraulics only Keep you out of ELEC EMER config. You will still be without G+Y hydraulic, in alternate law with only spoiler no.3 available so not much of help and with stab frozen. Approach speed is Weight+103kt and gear has to be by gravity atleast at 1000ft can be taken early but not late. That puts you in direct law so get Vapp before that. No Flap3 either as flaps at zero and slat 2&3 is same. Gliding distance will be height×2.