The choice of HSI mode or MAP mode when flying the ILS
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The choice of HSI mode or MAP mode when flying the ILS
During an ILS, it is sometimes left to the discretion of the captain if both MAP displays are displayed and the ILS flown using the PFD or ADI localiser display.
Some years ago the FAA mandated one pilot should have the ADI localiser on the screen rather than both pilots as above, due to evidence of MAP shift in some areas.
With more and more rigid standardisation of SOP demanded by some operators, the choice of whether one pilot should have the HSI mode and the other pilot the MAP mode displayed as cross reference, has largely removed the captain's decision on which presentation he prefers. This is not necessarily a good thing in my opinion.
We all have personal preferences of course, and mine is to have the HSI -ILS display on my side when PF.
Can any Pprune reader tell me if either the British CAA or the US FAA have a ruling on this choice - or if the Flight Manual for the aircraft type has such a limitation? My work involves the B737-300 simulator, which is where the question of SOP has arisen. Obviously MAP shift has to be considered and unnoticed MAP shift is potentially dangerous if the user is primarily using the MAP display for situational awareness.
While some insist that having MAP up display on both sides of the flight deck encourages increased "situational awareness - nevertheless this is a personal viewpoint as the standard HSI display on which to fly an ILS has been in operations for 50 years or more and has adequate situational awareness capability - hence the term HSI.
Some years ago the FAA mandated one pilot should have the ADI localiser on the screen rather than both pilots as above, due to evidence of MAP shift in some areas.
With more and more rigid standardisation of SOP demanded by some operators, the choice of whether one pilot should have the HSI mode and the other pilot the MAP mode displayed as cross reference, has largely removed the captain's decision on which presentation he prefers. This is not necessarily a good thing in my opinion.
We all have personal preferences of course, and mine is to have the HSI -ILS display on my side when PF.
Can any Pprune reader tell me if either the British CAA or the US FAA have a ruling on this choice - or if the Flight Manual for the aircraft type has such a limitation? My work involves the B737-300 simulator, which is where the question of SOP has arisen. Obviously MAP shift has to be considered and unnoticed MAP shift is potentially dangerous if the user is primarily using the MAP display for situational awareness.
While some insist that having MAP up display on both sides of the flight deck encourages increased "situational awareness - nevertheless this is a personal viewpoint as the standard HSI display on which to fly an ILS has been in operations for 50 years or more and has adequate situational awareness capability - hence the term HSI.
I remember the boeing 757-AFM had phrasing regarding map shift,...and a recomendation that the PF had HSI mode for the reasons you's explained
and to me it's the proper way
as far as regulations go in FAA-land don't think any legal restriction apllies
PA
and to me it's the proper way
as far as regulations go in FAA-land don't think any legal restriction apllies
PA
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How is the ADI Loc and G/s display different from HSI other than having a big long CDI instead of a diamond? The ADI ILS info is raw data isn't it?
The only reason for for HSI ILS or expanded ILS would be for when you need the ILS DME and you can't get it on the normal DME readouts (which I dont think the 737 has an issue with) - but other Boeings do (ie 767 can only get ILS DME readout when expanded ILS is used)
Also whilst maps can be quite a long way off in the terminal area, the most accurate map updates come of ILS DME dont they - so by the time you commence an ILS they should be pretty good.
I am still surprised that Boeing/FAA or the relevant authorities haven't mandated that all large commercial jets have Map updating via GPS yet.
The only reason for for HSI ILS or expanded ILS would be for when you need the ILS DME and you can't get it on the normal DME readouts (which I dont think the 737 has an issue with) - but other Boeings do (ie 767 can only get ILS DME readout when expanded ILS is used)
Also whilst maps can be quite a long way off in the terminal area, the most accurate map updates come of ILS DME dont they - so by the time you commence an ILS they should be pretty good.
I am still surprised that Boeing/FAA or the relevant authorities haven't mandated that all large commercial jets have Map updating via GPS yet.
Last edited by blueloo; 5th Feb 2009 at 03:59.
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Our SOP recommends (but of course you can deviate) that both use MAP if you have two FMC and two GPS receivers. That still leaves you with the raw data ILS indication on the PFD which is an approved crosscheck.
If you have only one FMC and/or only one GPS it is recommended that one pilot, preferrably the PF, use expanded ILS mode.
All that for the 737, but our classics have been phased out by now.
If you have only one FMC and/or only one GPS it is recommended that one pilot, preferrably the PF, use expanded ILS mode.
All that for the 737, but our classics have been phased out by now.
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What exactly happens in a Map Shift ? How and why ? Seams like it has never happened to me and havent heard of it yet from anyone that I flew with ..
http://www.aaib.gov.uk/cms_resources...0Report%20.pdf
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Our classic SOP is to have the split HSI (PF) and Map (PNF) for the reasons above. You just have to watch out for the variation database to be accurate before using the track line!
Thread Starter
Using MAP mode and the ADI ILS display. The localiser display on the ADI is by its design quite tiny compared to the HSI localiser display. 737 Classics.
If for whatever reason the aircraft deviates outside the expanded ADI localiser display it becomes a no-man's land because you don't know by how far the aircraft is off the ILS inbound course. All you know is you are more than one dot.
On the other hand, regardless of the expanded Localiser scale on the ADI, the HSI displays the full monty (all the dots) and allows the crew to see how far they are off centreline. This allows quicker situational awareness than the MAP mode in that a go around assessment is more readily available. Once the aircraft is even momentarily outside the expanded localiser scale on the ADI it becomes sheer guesswork to know how far off track it is.
If for whatever reason the aircraft deviates outside the expanded ADI localiser display it becomes a no-man's land because you don't know by how far the aircraft is off the ILS inbound course. All you know is you are more than one dot.
On the other hand, regardless of the expanded Localiser scale on the ADI, the HSI displays the full monty (all the dots) and allows the crew to see how far they are off centreline. This allows quicker situational awareness than the MAP mode in that a go around assessment is more readily available. Once the aircraft is even momentarily outside the expanded localiser scale on the ADI it becomes sheer guesswork to know how far off track it is.
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Denti
Isn't that putting the cart before the horse? The ILS display isn't there to crosscheck the map, it's there to be flown and for PF to act on the deviations indicated. Flying the map is really the realm of GNSS approaches is it not? We can still fly an ILS with an ANP > 0.3 after all.
Our SOP recommends (but of course you can deviate) that both use MAP if you have two FMC and two GPS receivers. That still leaves you with the raw data ILS indication on the PFD which is an approved crosscheck.
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Map = situational awareness.
Loc capture = Map update.
Classic (non-GPS) = possible map shift uptil Loc capture.
GPS a/c = should be very accurate all the time.
PFD Loc & G/S = raw data back up, but small scale.
SBY ADI ILS = Full scale deviation nof Loc + G/S.
Thus Map + SBY ADI has all the info you need in a neat package. Both pilots are looking at the same info. Was this not one of the debates about HUD's? LHS pilot flies HUD, RHS pilots monitors via raw data. They are not looking at the same info display.
The use of APP mode on HSI (ND) IMHO is only relevant if hand flying, and then only with no F.D. It is invaluable to lay the TK line over the ILS display. Piece of cake. Personally I also find this easier when flying a SE ILS even with F.D. It helps me 'lead' the FD and be proactive to prevent to many FD corrective commands.
The business of not knowing your deviation on the PFD/ADI outside 1 dot is a red herring. If you are flying manulaly with the F.D how have you allowed the a/c to be so far displaced?
Loc capture = Map update.
Classic (non-GPS) = possible map shift uptil Loc capture.
GPS a/c = should be very accurate all the time.
PFD Loc & G/S = raw data back up, but small scale.
SBY ADI ILS = Full scale deviation nof Loc + G/S.
Thus Map + SBY ADI has all the info you need in a neat package. Both pilots are looking at the same info. Was this not one of the debates about HUD's? LHS pilot flies HUD, RHS pilots monitors via raw data. They are not looking at the same info display.
The use of APP mode on HSI (ND) IMHO is only relevant if hand flying, and then only with no F.D. It is invaluable to lay the TK line over the ILS display. Piece of cake. Personally I also find this easier when flying a SE ILS even with F.D. It helps me 'lead' the FD and be proactive to prevent to many FD corrective commands.
The business of not knowing your deviation on the PFD/ADI outside 1 dot is a red herring. If you are flying manulaly with the F.D how have you allowed the a/c to be so far displaced?
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"Personally I also find this easier when flying a SE ILS even with F.D. It helps me 'lead' the FD and be proactive to prevent to many FD corrective commands."
You have to be careful not to lead the FD too much. It intentionally crosses the LOC centerline on an angled capture, to assure the other lobe is there. The failure can be in either the ground transmitter, or your receiver.
That's how it was told by a Fright Director design engineer.
GB
You have to be careful not to lead the FD too much. It intentionally crosses the LOC centerline on an angled capture, to assure the other lobe is there. The failure can be in either the ground transmitter, or your receiver.
That's how it was told by a Fright Director design engineer.
GB
Thread Starter
The business of not knowing your deviation on the PFD/ADI outside 1 dot is a red herring. If you are flying manulaly with the F.D how have you allowed the a/c to be so far displaced?
The HSI mode is there for an operational purpose; otherwise it would not be installed. A wise pilot utilises various display modes without being too rigid on any one.
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I used to find it irritating on the 734 when the F/O set up his own display and CDU and then told me what he wanted displayed on mine. When I first when on the fleet the principle was that PF chooses what he wants then PNF monitors him by displaying what he feels comfortable with. We then got some new training Captains who started teaching the new F/O's this habit of trying to tell the Captain what he should be displaying but to my mind it stops him from properly monitoring. If he wants map fine, if he wants another display then that should also be his choice, likewise the CDU page.
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If your going to mix your nav sensors when flying a precision approach based on an ILS i would recommend at least doing a RAIM check before you start the approach. Personally I believe the map display to be an irrelevant distraction when commencing a precision approach based on an ILS. I don't think I'm alone in that view either.
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"LOC" instead of MAP is only required if ILS/DME data is needed for tha approach.
Other than that you can use the expanded ILS display on the PFD.
If you can't track the ILS on the PFD...
MAP shift is the least of your problems.
Other than that you can use the expanded ILS display on the PFD.
If you can't track the ILS on the PFD...
MAP shift is the least of your problems.
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Denti
Quote:
Isn't that putting the cart before the horse? The ILS display isn't there to crosscheck the map, it's there to be flown and for PF to act on the deviations indicated. Flying the map is really the realm of GNSS approaches is it not? We can still fly an ILS with an ANP > 0.3 after all.
Quote:
Our SOP recommends (but of course you can deviate) that both use MAP if you have two FMC and two GPS receivers. That still leaves you with the raw data ILS indication on the PFD which is an approved crosscheck.
Flying raw data i would allways use an expanded ILS view or even full rose mode (which is more fun imo).
Thread Starter
Flying raw data i would allways use an expanded ILS view
If you have the FD off the ADI localiser gives you normal scale - not expanded.
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Sorry, i was talking about ND modes. Expanded (normal) vs full rose (one press on the CTR button) on the NG or EXP ILS/VOR vs FULL ILS/VOR.
The PFD expanded display is automaticly switched and i would prefer the expanded view over the full when flying raw data to be honest (more than dot off the loc is a mandatory go-around except for the intercept phase).
The PFD expanded display is automaticly switched and i would prefer the expanded view over the full when flying raw data to be honest (more than dot off the loc is a mandatory go-around except for the intercept phase).