How do you fly your non-precision approaches?
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How do you fly your non-precision approaches?
In my company non-precision approaches are flown as "continuous descent approach" down to the Minimum Descent Altitude - MDA.
When reaching the MDA (with a descent rate of about 600 to 800 fpm) the decision is made to continue or to start the missed approach.
In the case of a missed aproach the airplane descends inevitabely below MDA before a climbrate is established again.
This violates the obstacle clearance height, which is in my opinion illegal and unsafe.
Our senior pilots do not see a problem.
Additionaly it is procedure to set the Missed Approach Altitude in the altitude window of the MCP during the final descent to MDA AND NOT the MDA itself.
I think that setting the MDA would be much safer in case of a pilot mistake (or even F...-up).
Any comments are appreciated!
When reaching the MDA (with a descent rate of about 600 to 800 fpm) the decision is made to continue or to start the missed approach.
In the case of a missed aproach the airplane descends inevitabely below MDA before a climbrate is established again.
This violates the obstacle clearance height, which is in my opinion illegal and unsafe.
Our senior pilots do not see a problem.
Additionaly it is procedure to set the Missed Approach Altitude in the altitude window of the MCP during the final descent to MDA AND NOT the MDA itself.
I think that setting the MDA would be much safer in case of a pilot mistake (or even F...-up).
Any comments are appreciated!
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That's the problem with the continuous descent profile (as contrasted from dive & drive), if the decision to execute a missed approach is done at MDA, an altitude loss usually results during the maneuver.
An alternative of course would be to set the altitude alert to MDA+50 feet (and altimeter bugs if fitted), thereby giving a reasonable margin for the missed approach climb, if needed.
Many operators use this procedure.
An alternative of course would be to set the altitude alert to MDA+50 feet (and altimeter bugs if fitted), thereby giving a reasonable margin for the missed approach climb, if needed.
Many operators use this procedure.
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With the advent of 'CDA'approaches the FAA in regard to terps agreed to the 'Go around' at MDA providing that the 'sag' aspect was reviewed in training(one wonders about the 'sag' at DH-thats why you leave the gear until'posative rate')...
Ergo Carriers ADD an additional buffer.Generally 50',but some also consider Weight,Temperature,and Abnormals such as engine out performance(+100")
Ergo Carriers ADD an additional buffer.Generally 50',but some also consider Weight,Temperature,and Abnormals such as engine out performance(+100")
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Pittsle says: "In my company, non-precision approaches are flown as "continuous descent approach" down to the Minimum Descent Altitude - MDA."
That's not practical to do everywhere. How would it work at RIO/SBGL if you're cleared for the DESCENT CHARLIE 1 ILS Rwy 15 with the Glide Slope out?
That's not practical to do everywhere. How would it work at RIO/SBGL if you're cleared for the DESCENT CHARLIE 1 ILS Rwy 15 with the Glide Slope out?
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1. MDA/H is a NOT a DECISION POINT (like on a ILS approach)
2. For Chrissakes, get your senior pilots to read their Jepps properly. If English is not your first language, I suggest that you get a good interpreter to translate the following:
"MDA/H - A specific altitude or height in a non precision or circling approach below which decent may not be made without visual reference "
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Folks,
MDA is not a DH.
We set the MDA in the AltSel and the PNF calls "100 above" as a warning and the PF levels off at or above the MDA while the PNF looks for the required visual reference.
A missed approach (depending upon the circumstances) is commenced no later than the Missed Approach point from not less than MDA.
This process will support continued approaches for circling or a missed approach crossing the company SOP stabilised approach VASI limit if continuing is pointless. It respects MDA as a hard limit in either case.
While we prefer a constant descent angle approach, we plan our NPA profiles to hit the MDA a bit below the normal glideslope to allow for commencement of level-off without immediately exceeding our VASI slope limit for landing, just in case it is a visibility issue more than a cloudbase issue. This process satisfies our CFIT risk management strategy.
Stay Alive,
MDA is not a DH.
We set the MDA in the AltSel and the PNF calls "100 above" as a warning and the PF levels off at or above the MDA while the PNF looks for the required visual reference.
A missed approach (depending upon the circumstances) is commenced no later than the Missed Approach point from not less than MDA.
This process will support continued approaches for circling or a missed approach crossing the company SOP stabilised approach VASI limit if continuing is pointless. It respects MDA as a hard limit in either case.
While we prefer a constant descent angle approach, we plan our NPA profiles to hit the MDA a bit below the normal glideslope to allow for commencement of level-off without immediately exceeding our VASI slope limit for landing, just in case it is a visibility issue more than a cloudbase issue. This process satisfies our CFIT risk management strategy.
Stay Alive,
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The legalities have been more than amply addressed here already and, in any event it's clear that the "senior pilots" don't see a problem with them. So I'll put that aspect to one side for the purpose of this post.
Those "senior pilots" might be more interested in the fact that each time they slip below the MDA, they're voiding the company's insurance policy! If the pilots aren't interested in that aspect, I'll bet the company will be.
Those "senior pilots" might be more interested in the fact that each time they slip below the MDA, they're voiding the company's insurance policy! If the pilots aren't interested in that aspect, I'll bet the company will be.
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Hi folks,
in my company, we fly non precision approaches fully configured. We set the MDA via the MCDU to have a bug on the altimeter band. The missed approach altitude is set in the FCU window to be prepared for a goaround. Arriving at the MDA (50ft to 100ft before, depends on aircraft weight) we select v/s or flight path vector to zero, to level off. While that, the PNF is watching out for visual references. Formally you have to continue to the missed approach point, where your missed approach segment starts. But most of the time, when you see the RWY at the missed approach point, you cannot make the landing, you are to close. You had to dive towards the RWY with a very high rate of descent. Thats prohibited according our SOP, max. ROD 1000 ft/min below 1000ft AGL. What I do is, I calculate my personal decision point to continue down to the RWY with a 3° path. Is the MDH 450 ft, my decision point is 1,5 NM before the threshold (plus / minus DME reading, because most of the time the DME is not installed next to the theshold). When I would start the final descent later, I couldn´t land my bus withing the touchdown zone - and there we allways should land.
Allways happy landings,
drive
in my company, we fly non precision approaches fully configured. We set the MDA via the MCDU to have a bug on the altimeter band. The missed approach altitude is set in the FCU window to be prepared for a goaround. Arriving at the MDA (50ft to 100ft before, depends on aircraft weight) we select v/s or flight path vector to zero, to level off. While that, the PNF is watching out for visual references. Formally you have to continue to the missed approach point, where your missed approach segment starts. But most of the time, when you see the RWY at the missed approach point, you cannot make the landing, you are to close. You had to dive towards the RWY with a very high rate of descent. Thats prohibited according our SOP, max. ROD 1000 ft/min below 1000ft AGL. What I do is, I calculate my personal decision point to continue down to the RWY with a 3° path. Is the MDH 450 ft, my decision point is 1,5 NM before the threshold (plus / minus DME reading, because most of the time the DME is not installed next to the theshold). When I would start the final descent later, I couldn´t land my bus withing the touchdown zone - and there we allways should land.
Allways happy landings,
drive
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For the benefit of COl and 4Dogs.
The discussion is about CANPA's, constant aspect non precision approaches. It doesn't take a genius to work out that the easiest way to fly a Non precision approach is to arrive at the MDA in the correct position to be able to land on the runway. If you fly past this point at MDA in level flight you will not be in a position to make a stable approach, rather 'the duck and dive'.
The MDA thus becomes your effective 'decision altitude' because you have reached it at the ideal distance from the runway.
The discussion is about CANPA's, constant aspect non precision approaches. It doesn't take a genius to work out that the easiest way to fly a Non precision approach is to arrive at the MDA in the correct position to be able to land on the runway. If you fly past this point at MDA in level flight you will not be in a position to make a stable approach, rather 'the duck and dive'.
The MDA thus becomes your effective 'decision altitude' because you have reached it at the ideal distance from the runway.
Using MDA as a DA in a continuous descent isn't quite the same as the DA for a precision approach. You're still not permitted to descend below the MDA, unlike a precision DA. This means the a/c must have either commenced the missed approach prior to reaching MDA or have reduced RoD enough to ensure inertia will not cause a bust below MDA when the missed approach is commenced.
Our company uses a Company minimum of MDA+50' as a buffer to minimise MDA busts.
Our company uses a Company minimum of MDA+50' as a buffer to minimise MDA busts.
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Pittsle- You are absolutely right with regard to setting the MDA. What type of aircraft do you fly? If you flew the B737, the Flight Crew Training Manual would tell you that the recommended altitude to set in the MCP window during descent to the MDA is the MDA!
If your senior pilots don't see a problem in descent below the MDA without visual reference(they taught this in like BASIC training) I'm kinda wondering how they got "SENIOR"???-- jus plain lucky... or have'nt flown into say Kathmandu!! It'll make em appreciate MDA and other insignificant things like "minimum crossing altitudes" on an approach.
No offence- you seem to be pretty much on the right track- good of you to question a procedure which may already be established by "SENIOR" people!
We fly NPAs working out a Visual Descent Point... i.e., reaching (or trying to!) be at the MDA at a distance out from the threshold from which a continous descent at a NORMAL descent rate could be made to landing. I poor visibility we'd probably like to get to the MDA a little earlier to give time to acquire the runway. If you have'nt got to the MDA by the VDP, you're pretty much sure of another 15 minutes of flight log book time.
If your senior pilots don't see a problem in descent below the MDA without visual reference(they taught this in like BASIC training) I'm kinda wondering how they got "SENIOR"???-- jus plain lucky... or have'nt flown into say Kathmandu!! It'll make em appreciate MDA and other insignificant things like "minimum crossing altitudes" on an approach.
No offence- you seem to be pretty much on the right track- good of you to question a procedure which may already be established by "SENIOR" people!
We fly NPAs working out a Visual Descent Point... i.e., reaching (or trying to!) be at the MDA at a distance out from the threshold from which a continous descent at a NORMAL descent rate could be made to landing. I poor visibility we'd probably like to get to the MDA a little earlier to give time to acquire the runway. If you have'nt got to the MDA by the VDP, you're pretty much sure of another 15 minutes of flight log book time.
I would have expected most Ppruner’s to have learnt by now that the safest method of flying a non precision approach is by using a stable, constant angle approach; then at MDA or the nominated height above, commence a go around if the required visual reference is not achieved.
For the uncommitted then please refer to the Flight Safety Foundation’s ALAR Training Tool Kit and the related CFIT accident examples. Do not forget to use the rad alt …? Yes it can be used as a safety instrument on an NPA. At 10 nm or greater from the airfield the charted procedure should always keep the aircraft above 2500 ft RA. Above 500 ft RA until the final fix, and thereafter always above 250 ft RA until MDA. For those who still duck under; then as soon as your airline fits TAWS; a) the safer we will all be and b) keep you hat ready for visits to the chief’s office to explain those TERRAIN alerts.
I understand that the risk due to height loss depends on which approach construction method is used. Those constructed with TERPS may have slightly more obstacle clearance (higher MDA); thus any loss of height below that is less significant than for approaches constructed with PANSOPS. I also understand that a JAA committee has reviewed a paper assessing the risk of using MDA as ‘DH’ i.e. accepting GA flight below MDA. There appears to be a very small increase in risk such that it could be ignored in comparison with the greatly reduced risk of a CFIT accident when flying CANAPA and using MDA as DH. I guess that any JAA decision will take another 10 committee stages and a year or five to agree yet another compromise.
Some of the most important issues seen in NPA accidents are the lack of planning - calculating required VS and timing, and the failure to use of constant airspeed. Investigations concluded that many crews were unaware of the hazards of making an approach at high constant VS and then decelerating. The effect of the decelerating airspeed without VS adjustment caused the flight path to be well below the expected vertical path; thus the flight path aims short of the runway. This error can be detected by use of alt / dist charts.
I hope that everyone now uses approach charts with tables of altitude vs distance;… and why can’t we have charts with the visual descent point (alt / dist) on them?
For the uncommitted then please refer to the Flight Safety Foundation’s ALAR Training Tool Kit and the related CFIT accident examples. Do not forget to use the rad alt …? Yes it can be used as a safety instrument on an NPA. At 10 nm or greater from the airfield the charted procedure should always keep the aircraft above 2500 ft RA. Above 500 ft RA until the final fix, and thereafter always above 250 ft RA until MDA. For those who still duck under; then as soon as your airline fits TAWS; a) the safer we will all be and b) keep you hat ready for visits to the chief’s office to explain those TERRAIN alerts.
I understand that the risk due to height loss depends on which approach construction method is used. Those constructed with TERPS may have slightly more obstacle clearance (higher MDA); thus any loss of height below that is less significant than for approaches constructed with PANSOPS. I also understand that a JAA committee has reviewed a paper assessing the risk of using MDA as ‘DH’ i.e. accepting GA flight below MDA. There appears to be a very small increase in risk such that it could be ignored in comparison with the greatly reduced risk of a CFIT accident when flying CANAPA and using MDA as DH. I guess that any JAA decision will take another 10 committee stages and a year or five to agree yet another compromise.
Some of the most important issues seen in NPA accidents are the lack of planning - calculating required VS and timing, and the failure to use of constant airspeed. Investigations concluded that many crews were unaware of the hazards of making an approach at high constant VS and then decelerating. The effect of the decelerating airspeed without VS adjustment caused the flight path to be well below the expected vertical path; thus the flight path aims short of the runway. This error can be detected by use of alt / dist charts.
I hope that everyone now uses approach charts with tables of altitude vs distance;… and why can’t we have charts with the visual descent point (alt / dist) on them?
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Thanks for the replies!!
I am really impressed by the numerous and very qualified replies to my question.
OzExpat:
Where can I get more information about the voiding of the companiy´s insurance policy? That is really interesting!
FlyinWithoutWings:
As a matter of fact I relly fly a 737/300. I know about the recommendation in the Boeing flight manual to set the MDA in the MCP window. I also think that is the better - and safer - way to go.
I will try once again and make the proposal to change the procedures to what seems to be international standards.
OzExpat:
Where can I get more information about the voiding of the companiy´s insurance policy? That is really interesting!
FlyinWithoutWings:
As a matter of fact I relly fly a 737/300. I know about the recommendation in the Boeing flight manual to set the MDA in the MCP window. I also think that is the better - and safer - way to go.
I will try once again and make the proposal to change the procedures to what seems to be international standards.
Those who set MDA in the MCP window take care.
I am not a Boeing driver but I am familiar with some of their operational recommendations and those given for other highly automated aircraft. On some aircraft the reason for selecting MDA in the MCP window is to enable the selection of vertical speed for descent on the final approach. (For those flight guidance systems requiring Alt Sel change before leaving an altitude.) After commencing the final approach many manufactures recommend that the missed approach altitude is set in the MCP. This avoids an unnecessary level off at MDA (which may encourage bad practice or destabilises the approach) and, with some systems could prevent false or misleading altitude capture during go around from below MDA. If a circling approach is planned then the circling altitude may be set.
Thus do not leave MDA in the MCP; if you require a MDA reminder use the DH bug, grease pencil (non EFIS), and even ‘the non flying pilot’!
If in doubt follow the manufactures procedures, they have been thought through against a background of deep system knowledge and in the fullness of time with the many experiences of many operators.
Thus do not leave MDA in the MCP; if you require a MDA reminder use the DH bug, grease pencil (non EFIS), and even ‘the non flying pilot’!
If in doubt follow the manufactures procedures, they have been thought through against a background of deep system knowledge and in the fullness of time with the many experiences of many operators.
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One other problem that might arise when setting the MDA in the MCP Altitude window, is that the A/C (depending on A/C type & FGS algorithms) might descend after pressing TOGA if you accidently leave the MDA in the MCP and engage a speed mode instead of leaving the GA mode active before changing the ALT SEL to a higher value than your current alt. The best is to stick to the manufacturer's procedures and be very careful in just accepting operator's/CAA's (no specific airline/country) quick fix solutions to the CANPA which stands for "Constant Angle NPA".
Safe Flying
Cheersh vir eersh
Safe Flying
Cheersh vir eersh
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Miserlou,
It also doesn't take a genius to read their Jepps and see that an MDA is a Minimum Descent Altitude (a hard limitation not to be violated unless visual) and NOT a Decision Altitude, which pertains to a Precision approach.
The decision to land or go around durning a NPA is based upon either being at or above the minima (MDA) and either being visual and able to make the landing, or not.
Don't mix the two up.
Regardless of whether the approach is flown with a constant rate of descent or 'dive and drive', I repeat, the MDA is a 'hard' limitation and should not be violated if not visual - period. The definition is pretty specific, and not open to interpretation.
Personally, I find it a sham that 'senior pilots' like these guys are flying transport category aircraft and are unable, or unwilling to, discern this very basic concept, whose definition is freely and clearly available.
And I bet that Pittsle is having a hard time trying to convince these guys that this is an unsafe practice.
My apologies if i seem atop a high horse, but please, this is pretty basic, yet dangerous, stuff to be anything but cruystal clear about.
Good luck, Pittsle.
It also doesn't take a genius to read their Jepps and see that an MDA is a Minimum Descent Altitude (a hard limitation not to be violated unless visual) and NOT a Decision Altitude, which pertains to a Precision approach.
The decision to land or go around durning a NPA is based upon either being at or above the minima (MDA) and either being visual and able to make the landing, or not.
Don't mix the two up.
Regardless of whether the approach is flown with a constant rate of descent or 'dive and drive', I repeat, the MDA is a 'hard' limitation and should not be violated if not visual - period. The definition is pretty specific, and not open to interpretation.
Personally, I find it a sham that 'senior pilots' like these guys are flying transport category aircraft and are unable, or unwilling to, discern this very basic concept, whose definition is freely and clearly available.
And I bet that Pittsle is having a hard time trying to convince these guys that this is an unsafe practice.
My apologies if i seem atop a high horse, but please, this is pretty basic, yet dangerous, stuff to be anything but cruystal clear about.
Good luck, Pittsle.
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In the bad old days, NPAs were NOT aligned with the runway in most cases in Australia so the MDA was in fact the circling altitude.
Quite properly the wisdom of runway aligned approaches has been seen and most are now of that persuasion.
Clasic ones such as Kathmandu come to mind as high sink rates etc can make the literal following of the law difficult in some cases.
No one should argue against the benifits of a stable sink/profile on final approach to any runway, ILS or NPA but be aware of the legalities, senior pilots who only fly in good WX when it's all a non event are a hazzard in their own right.
Just think how it will sound at the Court of Enquiry and act accordingly.
Quite properly the wisdom of runway aligned approaches has been seen and most are now of that persuasion.
Clasic ones such as Kathmandu come to mind as high sink rates etc can make the literal following of the law difficult in some cases.
No one should argue against the benifits of a stable sink/profile on final approach to any runway, ILS or NPA but be aware of the legalities, senior pilots who only fly in good WX when it's all a non event are a hazzard in their own right.
Just think how it will sound at the Court of Enquiry and act accordingly.