RNAV missed approach
Weird question.
Is everything working correctly? Was the approach flown within lateral/vertical limits to the minimum? Be more specific please, though it seems you are holding some trick answer to catch a responder.
Is everything working correctly? Was the approach flown within lateral/vertical limits to the minimum? Be more specific please, though it seems you are holding some trick answer to catch a responder.
Thread Starter
Join Date: Sep 2017
Location: Malta
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
i don’t know the answer. Someone asked me this and I genuinely have no idea of the possible reason.
I would say that you cannot execute an RNAV missed approach, when the reason for going missed was a failure of the RNAV/GNSS system itself.
My understanding is that in this instance, you need to either revert to a conventional terrestrial aid (ie. VOR/NDB) or possibly Dead Reckoning navigation.
Note that you must continue to use the RNAV if the reason for aborting was independent of the RNAV/GNSS system. However, if the reason was loss of RNAV guidance, you need an "extraction procedure", which is dead reckoning to a safe altitude.
I can't find a "proper" reference for any of this, but I haven't had a thorough search through the rules and regs as yet.
My understanding is that in this instance, you need to either revert to a conventional terrestrial aid (ie. VOR/NDB) or possibly Dead Reckoning navigation.
Originally Posted by https://skybrary.aero/bookshelf/books/2315.pdf
3.5.1.3 RNAV protected missed approach (not relying on conventional radionavigation means)
If the missed approach flight path is an RNAV procedure and if the approach has to be aborted for a reason independent of the operation of the RNAV/GNSS system, the crew must continue to use RNAV/GNSS system guidance to follow the missed approach procedure.
Extraction procedure
If the missed approach path is a RNAV procedure: The operator may have defined previously in their procedures, an emergency procedure for the case where the loss of RNAV guidance during the approach does not allow to follow the missed approach procedure provided for the considered runway. This emergency procedure will consist in following a dead reckoning path, allowing to reach a sufficient altitude and taking into account: - obstacles - aircraft performance - airspace restrictions
If the missed approach flight path is an RNAV procedure and if the approach has to be aborted for a reason independent of the operation of the RNAV/GNSS system, the crew must continue to use RNAV/GNSS system guidance to follow the missed approach procedure.
Extraction procedure
If the missed approach path is a RNAV procedure: The operator may have defined previously in their procedures, an emergency procedure for the case where the loss of RNAV guidance during the approach does not allow to follow the missed approach procedure provided for the considered runway. This emergency procedure will consist in following a dead reckoning path, allowing to reach a sufficient altitude and taking into account: - obstacles - aircraft performance - airspace restrictions
I can't find a "proper" reference for any of this, but I haven't had a thorough search through the rules and regs as yet.
Join Date: Oct 2004
Location: mids
Age: 59
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
Visual is the same missed approach in Europe and most places in the world. FAA land apparently its different.
Now the screw ups that can happen during the missed approach are various and not related to aircraft type.
If you say have a straight ahead climbing then after a certain alt turn back towards a beacon/fix which you pass during going straight ahead you will have problems if you have tried to fly in LNAV the climb. What happens is that as soon as the plane passes the beacon it thinks the procedure is finished with and gives up.
Next one is in high performance aircraft and the beacon is close behind you and the turn altitude is lowish it will start turning at the alt. Because you will still be close to the beacon the aircraft will never be able to get its nose pointing at the fix so you will end up circling it at max bank for the autopilot.
That's the most common gotcha's, Simple solution is just to stay in heading mode until your a decent distance away then give it a turn back towards the beacon.
Now the screw ups that can happen during the missed approach are various and not related to aircraft type.
If you say have a straight ahead climbing then after a certain alt turn back towards a beacon/fix which you pass during going straight ahead you will have problems if you have tried to fly in LNAV the climb. What happens is that as soon as the plane passes the beacon it thinks the procedure is finished with and gives up.
Next one is in high performance aircraft and the beacon is close behind you and the turn altitude is lowish it will start turning at the alt. Because you will still be close to the beacon the aircraft will never be able to get its nose pointing at the fix so you will end up circling it at max bank for the autopilot.
That's the most common gotcha's, Simple solution is just to stay in heading mode until your a decent distance away then give it a turn back towards the beacon.
Last edited by tescoapp; 28th Jan 2019 at 13:31.
