ADF and Drift
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Quote Leadsled
I gather you are referring to the 5nm 'buffer' around the holding pattern, which also allows for a "an omnidirectional wind of 60 kt".
However the rules also say
and
Therefore you should try to adjust heading to maintain the magenta line, and only then if unable to follow the line can you rely upon the inbuilt buffers in the procedure design.
PS1: Hint: The "racetrack" is a charting depiction of a holding pattern, not a track to fly.
It would be a good idea to actually read the rules for a holding patter, and consequently the actual shape of the obstacle protected area -- and the design rules for flying to remain inside....... What he was trying to say is that procedure design does not require drift correction to stay withing the protected area.
As some of you will be aware, we have had several recent incidents, where a pilot had tried to track the pretty little "racetrack" on their screen (not required) with some interesting results, when the bank angle limit was overridden to try and stay on the pink ( Sorry, "magenta") line in the turn.
As some of you will be aware, we have had several recent incidents, where a pilot had tried to track the pretty little "racetrack" on their screen (not required) with some interesting results, when the bank angle limit was overridden to try and stay on the pink ( Sorry, "magenta") line in the turn.
However the rules also say
FLIGHT PROCEDURES (DOC 8168) - GENERAL PRINCIPLES
Extracted from ICAO Document 8168, Volume I - Fifth Edition — Flight Procedures, PROCEDURES FOR AIR NAVIGATION SERVICES — AIRCRAFT OPERATIONS, herein known as PANS-OPS.
1 GENERAL INFORMATION
1.1 GENERAL
1.1.2 Procedures contained in PANS-OPS assume that all engines are operating.
NOTE: Development of contingency procedures is the responsibility of the operator.
1.1.3 All procedures depict tracks. Pilots should attempt to maintain the track by applying corrections to heading for known wind.
Extracted from ICAO Document 8168, Volume I - Fifth Edition — Flight Procedures, PROCEDURES FOR AIR NAVIGATION SERVICES — AIRCRAFT OPERATIONS, herein known as PANS-OPS.
1 GENERAL INFORMATION
1.1 GENERAL
1.1.2 Procedures contained in PANS-OPS assume that all engines are operating.
NOTE: Development of contingency procedures is the responsibility of the operator.
1.1.3 All procedures depict tracks. Pilots should attempt to maintain the track by applying corrections to heading for known wind.
FLIGHT PROCEDURES (DOC 8168) - HOLDING PROCEDURES
1.3.3 Allowance for known wind
All procedures depict tracks. Pilots should attempt to maintain the track by making allowance for known wind by applying corrections both to heading and timing.
This should be done during entry and while flying in the holding pattern.
3.3.6 Wind effect
3.3.6.1 To achieve a stabilized approach, due allowance should be made in both heading and timing to compensate for the effects of wind so that the aircraft regains the inbound track as accurately and
expeditiously as possible. In making these corrections, full use should be made of the indications available from the aid and from estimated or known winds.
This is particularly important for slow aircraft in high wind conditions, when failure to compensate may render the procedure unflyable (i.e. the aircraft may pass the fix before establishing on the inbound track) and it could depart outside the protected area).
1.3.3 Allowance for known wind
All procedures depict tracks. Pilots should attempt to maintain the track by making allowance for known wind by applying corrections both to heading and timing.
This should be done during entry and while flying in the holding pattern.
3.3.6 Wind effect
3.3.6.1 To achieve a stabilized approach, due allowance should be made in both heading and timing to compensate for the effects of wind so that the aircraft regains the inbound track as accurately and
expeditiously as possible. In making these corrections, full use should be made of the indications available from the aid and from estimated or known winds.
This is particularly important for slow aircraft in high wind conditions, when failure to compensate may render the procedure unflyable (i.e. the aircraft may pass the fix before establishing on the inbound track) and it could depart outside the protected area).
Therefore you should try to adjust heading to maintain the magenta line
Clinton,
I refer again to the CASA article some years ago, and the procedure design criteria that was referred to, nothing more. The CASA article was generally correct, but not well expressed, you needed "to know the answer to understand the question".
Likewise, review what I actually said, not what you think I said.
The procedure design does not require allowance for known wind to remain within protected area. However, most of us have always allowed for wind/drift, using any of the various rules of thumb quoted in various posts --- nice and neat and tidy, sort of, until you look at radar track records of pilots flying holding patterns in a non-FMCS or similar equipped aircraft ----- Then you understand why the shape of the protected area is as it is ----- What looks neat and tidy to us in the cockpit, looks quite different to the radar man.
But --- Remaining within the protected area does not require the application of any rule of thumb of choice (within the limits of the design wind) ---- but where the CASA article was wrong, was to suggest that making allowances for wind could put you outside the protected area.
Similar confusion frequently occurs about where to point the aeroplane after takeoff: Does runway heading mean runway QDM, runway QDM adjusted for drift (ie track) or something else. Unfortunately, for international pilots, the answer is location specific.
Tootle pip!!
PS: One country used to (and maybe still does - my license there is no longer current) quote holding pattern times as "beacon to beacon", and quotes timing the inbound leg ---- meaning you have to adjust the angle of bank in the two turns, and the outbound timings, to achieve the accuracy to pass an IR renewal ---- no FMCS systems allowed ---- makes it quite sporting --- +/- 15 seconds, "beacon the beacon" was(is?) the criteria.
PS2: As the Pans/Ops 8136 recommendations are not a requirement, what should you "examine" here on a renewal. My opinion is that, as long as the protected area is not broached, and the subsequent letdown is always within tracking limits (which obviously is easier if you are well settled on the inbound track before leaving the holding or other procedural altitude) it is a pass thus far. I will be interested in other ideas.
I refer again to the CASA article some years ago, and the procedure design criteria that was referred to, nothing more. The CASA article was generally correct, but not well expressed, you needed "to know the answer to understand the question".
Likewise, review what I actually said, not what you think I said.
The procedure design does not require allowance for known wind to remain within protected area. However, most of us have always allowed for wind/drift, using any of the various rules of thumb quoted in various posts --- nice and neat and tidy, sort of, until you look at radar track records of pilots flying holding patterns in a non-FMCS or similar equipped aircraft ----- Then you understand why the shape of the protected area is as it is ----- What looks neat and tidy to us in the cockpit, looks quite different to the radar man.
But --- Remaining within the protected area does not require the application of any rule of thumb of choice (within the limits of the design wind) ---- but where the CASA article was wrong, was to suggest that making allowances for wind could put you outside the protected area.
Similar confusion frequently occurs about where to point the aeroplane after takeoff: Does runway heading mean runway QDM, runway QDM adjusted for drift (ie track) or something else. Unfortunately, for international pilots, the answer is location specific.
Tootle pip!!
PS: One country used to (and maybe still does - my license there is no longer current) quote holding pattern times as "beacon to beacon", and quotes timing the inbound leg ---- meaning you have to adjust the angle of bank in the two turns, and the outbound timings, to achieve the accuracy to pass an IR renewal ---- no FMCS systems allowed ---- makes it quite sporting --- +/- 15 seconds, "beacon the beacon" was(is?) the criteria.
PS2: As the Pans/Ops 8136 recommendations are not a requirement, what should you "examine" here on a renewal. My opinion is that, as long as the protected area is not broached, and the subsequent letdown is always within tracking limits (which obviously is easier if you are well settled on the inbound track before leaving the holding or other procedural altitude) it is a pass thus far. I will be interested in other ideas.
Last edited by LeadSled; 28th Feb 2010 at 00:50.
I think I understand what he is trying to say.
He is implying that the depicted holding pattern on the chart is not required to tracked but is a representation of what the holding pattern should look like.
An A380 doing a rate 1 turn from overhead the aid to track outbound at 200 knots is going to fly a much wider holding pattern than a C172 at 90. He is basically saying that the guys who try to programme the hold into the FMC and have the aircraft flying the exact depiction of the holding pattern from the chart could be doing so at their own peril, especially if they are trying to maintain the rate of turn from outbound to inbound as depicted on the chart.
In regards to an allowance for wind it is simply good airmanship. The more accurate you estimate drift on the outbound leg the easier the intercept of the inbound track to the aid. While most of us use the suck it and see method I like to give myself a bit of a margin here as it is much easier to regain track in an undershoot than an overshoot.
He is implying that the depicted holding pattern on the chart is not required to tracked but is a representation of what the holding pattern should look like.
An A380 doing a rate 1 turn from overhead the aid to track outbound at 200 knots is going to fly a much wider holding pattern than a C172 at 90. He is basically saying that the guys who try to programme the hold into the FMC and have the aircraft flying the exact depiction of the holding pattern from the chart could be doing so at their own peril, especially if they are trying to maintain the rate of turn from outbound to inbound as depicted on the chart.
In regards to an allowance for wind it is simply good airmanship. The more accurate you estimate drift on the outbound leg the easier the intercept of the inbound track to the aid. While most of us use the suck it and see method I like to give myself a bit of a margin here as it is much easier to regain track in an undershoot than an overshoot.
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First of all an apology and an update from my previous post.
I quoted "60knot omnidirectional wind" (+5nm buffer) This has been updated to ICAO standard wind = "2(height in 1000 ft) + 47 knots" (+ 5nm buffer) for the procedure design.
You also persist with stating
which is at odds with the caution in the AIP
I think Capt. Fathom may be hint hinting at the USA holding rules where you can find his arguments in AIM 5-3-7
and
I've got a little hint to. Our speeds differ from the USA rules. hint hint
GG - All FMC aircraft I've operated, including the A380 will render the magenta line in accordance with the procedure design and if unable to fly the track the autopilot will regain track as soon as possible using its normal maximum allowed angle of bank, depending on speed and aircraft configuration, almost as well as a good pilot could.
I quoted "60knot omnidirectional wind" (+5nm buffer) This has been updated to ICAO standard wind = "2(height in 1000 ft) + 47 knots" (+ 5nm buffer) for the procedure design.
You also persist with stating
The procedure design does not require allowance for known wind to remain within protected area.
FLIGHT PROCEDURES (DOC 8168) - HOLDING PROCEDURES
1.3.3 Allowance for known wind
All procedures depict tracks. Pilots should attempt to maintain the track by making allowance for known wind by applying corrections both to heading and timing.
This should be done during entry and while flying in the holding pattern.
3.3.6 Wind effect
3.3.6.1 ...due allowance should be made in both heading and timing to compensate for the effects of wind so that the aircraft regains the inbound track as accurately and expeditiously as possible. ...
This is particularly important for slow aircraft in high wind conditions, when failure to compensate may render the procedure unflyable (i.e. the aircraft may pass the fix before establishing on the inbound track and it could depart outside the protected area).
1.3.3 Allowance for known wind
All procedures depict tracks. Pilots should attempt to maintain the track by making allowance for known wind by applying corrections both to heading and timing.
This should be done during entry and while flying in the holding pattern.
3.3.6 Wind effect
3.3.6.1 ...due allowance should be made in both heading and timing to compensate for the effects of wind so that the aircraft regains the inbound track as accurately and expeditiously as possible. ...
This is particularly important for slow aircraft in high wind conditions, when failure to compensate may render the procedure unflyable (i.e. the aircraft may pass the fix before establishing on the inbound track and it could depart outside the protected area).
I think Capt. Fathom may be hint hinting at the USA holding rules where you can find his arguments in AIM 5-3-7
Holding pattern airspace protection is based on the following procedures.
1. Descriptive Terms.
(a) Standard Pattern. Right turns
(See FIG 5-3-3.)
(b) Nonstandard Pattern. Left turns
2. Airspeeds.
(a) All aircraft may hold at the following altitudes and maximum holding airspeeds:
TBL 5-3-1
Altitude (MSL) Airspeed (KIAS)
MHA - 6,000' 200
6,001' - 14,000' 230
14,001' and above 265
1. Descriptive Terms.
(a) Standard Pattern. Right turns
(See FIG 5-3-3.)
(b) Nonstandard Pattern. Left turns
2. Airspeeds.
(a) All aircraft may hold at the following altitudes and maximum holding airspeeds:
TBL 5-3-1
Altitude (MSL) Airspeed (KIAS)
MHA - 6,000' 200
6,001' - 14,000' 230
14,001' and above 265
Compensate for wind effect primarily by drift correction on the inbound and outbound legs. When outbound, triple the inbound drift correction to avoid major turning adjustments; e.g., if correcting left by 8 degrees when inbound, correct right by 24 degrees when outbound.
GG - All FMC aircraft I've operated, including the A380 will render the magenta line in accordance with the procedure design and if unable to fly the track the autopilot will regain track as soon as possible using its normal maximum allowed angle of bank, depending on speed and aircraft configuration, almost as well as a good pilot could.
Last edited by Back Seat Driver; 3rd Mar 2010 at 09:34. Reason: additional info
