Agree with MarcK and others! Bottom line is:
You have been cleared for all the procedures on the plate in front of you (and any NOTAM'd amendments). You don't need to request to change to localiser minimums. You can just do it. However, there may be 100 other reasons why you wouldn't.
The main reason touches on the stabilised approach concept with respect to 'workload'. If switching requires a deviation from approach brief, major level changes or aircraft configuration changes (climbs, flaps, power, attitude, speed), navaid switching, chart and plate checking, or any other procedure which increases workload significantly, then I would go-around.
By that statement then, it depends on so many factors. One pilot might elect to go around, another might elect to switch. No correct answer.
Below are a number of observations on this thread so far.
Paco said:
In an airline, the commercial department will love you if you keep overshooting and unnecessarily wasting fuel.
Yes this might be the case in some airlines. In others though, you would be definitely not allowed to continue (depending on where you are in the approach). This relates to the 'stabilised approach' concept, where, with loss of glideslope beyond a certain altitude (or FAF) renders you un-stabilised. Not so much an issue with helos, but definitely in the FW world.
SASless: I don't understand how GS-failure caused the crash you describe in post #5. You do bring up a point though. In US if you inform that you are going to be doing a coupled approach, the controller should put you 2 miles outside the approach gate.
BigKahuna said:
There is no correct single answer to your question, it depends where you are on the approach.
I perfectly agree. It also depends on the complexity of the LOC-only approach and how well you know it off by heart. At the point of GS loss, you MUST be sure that you are above the non-precision minimums. If there is any doubt, I would go-around immediately. This could happen where the non-precision approach (LOC-only) is a complex step down approach.
800 said:
This indicates that you have already established the approach and the aid (either on the ground or in the aircraft) has become unserviceable OR is out of tolerance. This then requires a missed approach.
Nope, because by going Loc-only, you are flying a procedure which does not require any of the 'unserviceable parts'. Remember the GS is on a totally separate receiving unit to the VOR / Loc system.
Hedski said:
I would be very surprised if an examiner could fail a candidate for choosing the apparent safe option,
Sometimes going around is not the safe option. This might be your last chance to get in, before the weather is forecasted to close in. You might be fuel critical. Again, a good examiner will discuss things here. He might fail a candidate for going around, thus not showing knowledge of all the options and regulations. (See Spinwing's last paragraph.)
Particularly in helicopters, sometimes the safer option (if available) is to simply couple everything up and bring the speed back and deal with the weather. With our range and endurance, go-arounds and alternates might not look so rosey.
Therefore if either failed half-way down the approach I would treat this in the same manner.
If you are half scale above the glideslope, you must discontinue using the GS for vertical navigation, due to the possibility of false glideslopes. However, this does not mean you cannot change to loc-only minimums.
If you are half scale below glideslope, then I would go around for sure.
ATCO2 asks:
When executing ILS/DME approach, DME because there are no markers, what do you pilots intend to do in case of DME failure. Will you go around immediately or you will continue ILS approach till DA/H?
I agree with Gomer here. The DME is not required for execution of the ILS approach. It is for identification of the FAF (intercept point) as an altimeter check height. It is also for the non-precision portion. So continue.
IHL said:
but the majority do have an NDB as the Final Approach Fix (FAF)-usually about 4.5 to 5 nm from the threshold.
Nope, just depends where you are! REMEMBER, the presence of NDB or some other marker at the FAF is purely for a non-precision approach procedure (LOC-only or some other NP approach). The FAF for an ILS is the point of intercept at the particular altitude. The FAF is not part of the ILS system. This is seen by the different types of ILSs which don’t have any marker at the FAF. (e.g. Radar vectored, ILS/DME)
A decent to localizer ONLY minimums (in the event of GS failure) would be done on timing from the FAF, i.e.cross the beacon start the time
This is not on every approach. In fact, timing is only used when the FAF is marked by station passage over a beacon. If there is a beacon at the MAP or MAP is defined by DME, then of course you won't be timing.
SASless:
How many of us brief the missed approach procedures prior to the start of the approach as a standard procedure?
Every time. Or at least the first part of it, then NFP will guide through rest!
IHL said:
Some guys do briefings that go on and on and on and on...,
SOPs help here greatly. Can cut a great deal out.
Well, that passed the time.
Comments welcome.
cl12pv2s
Last edited by cl12pv2s; 28th Mar 2007 at 23:15.