Altitude or speed restriction?
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Altitude or speed restriction?
Scenario: Inbound on a star. The star has an altitude restriction and I'm on profile with indicated 300 kts. ATC tells me to reduce to 250. This speed reduction will take me above the max altitude at point X, even with speed brakes extended.
Assuming I can't get through on the freq, which restriction is the most limiting? We are talking a delay of 2-3 minutes with the speed reduction in order to meet the altitude.
Assuming I can't get through on the freq, which restriction is the most limiting? We are talking a delay of 2-3 minutes with the speed reduction in order to meet the altitude.
Join Date: Jan 2003
Location: Southampton
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Morning! I'm not sure where you fly but certainly in the UK it's quite a common scenario these days. Every situation is unique but here are some pointers from an LTMA perspective:
Generally, we work on a height first then speed basis. If you are no longer able to meet the vertical restriction then you should advise ATC as there may be implications and some situations would require a change in priorities. When I'm in such a situation I tend to use a non-standard phrase such as "EZY8888 (or indeed RYR7777 - had that callsign today and it's ruddy difficult to get out especially when there's a 1077 and 707 on freq too....) reduce speed 220kts, then descend FL XYZ". This might apply for example if you're catching up the a/c in front a bit sharpish...
You mentioned a situation where the RT is too busy to get in so I'd go with the height restriction first if you can't do both. Often the speed reduction is an indication of congestion ahead and it's one tool at our disposal to delay your arrival at the hold to reduce the likelihood of holding and making sure there's a level for your there. If you do manage to get in on the RT and ask, it is not usually a big issue if you are high at the given point as most of our standing agreements are there to ensure that you enter the correct person's airspace and provide a degree of 'procedural separation' from other routes (for planning and RT fail purposes). Once you're talking to a controller with a radar these become secondary.
One additional thing to consider is that you mention you're following a STAR with a level restriction. If you are basing that on the published STAR the levels mentioned are for 'descent PLANNING only'. Unless they are stipulated with the relevant ATC instruction then they do not apply.
Hope this helps
CT
Generally, we work on a height first then speed basis. If you are no longer able to meet the vertical restriction then you should advise ATC as there may be implications and some situations would require a change in priorities. When I'm in such a situation I tend to use a non-standard phrase such as "EZY8888 (or indeed RYR7777 - had that callsign today and it's ruddy difficult to get out especially when there's a 1077 and 707 on freq too....) reduce speed 220kts, then descend FL XYZ". This might apply for example if you're catching up the a/c in front a bit sharpish...
You mentioned a situation where the RT is too busy to get in so I'd go with the height restriction first if you can't do both. Often the speed reduction is an indication of congestion ahead and it's one tool at our disposal to delay your arrival at the hold to reduce the likelihood of holding and making sure there's a level for your there. If you do manage to get in on the RT and ask, it is not usually a big issue if you are high at the given point as most of our standing agreements are there to ensure that you enter the correct person's airspace and provide a degree of 'procedural separation' from other routes (for planning and RT fail purposes). Once you're talking to a controller with a radar these become secondary.
One additional thing to consider is that you mention you're following a STAR with a level restriction. If you are basing that on the published STAR the levels mentioned are for 'descent PLANNING only'. Unless they are stipulated with the relevant ATC instruction then they do not apply.
Hope this helps
CT
Join Date: Oct 2006
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Hi,
If you're on the STAR inbound to a point speed 300 Knts and you will be crossing a POINT at the desired FL:
"Instruction" : Speed 250 kts ==> You apply the instruction 250 kts (readback).
Of course you can tell the controller Reducing 250, unable to comply with altitude restriction blablabla.
Don't think about reducing "after" the point ... just do it when instructed. This will keep you out of problems. If there is a problem with the ALTITUDE, the controller will (hopefully) see this on radar and take the necessary action (if needed).
The instruction to reduce (especially in EBBU) is only given when needed. For seraration purposes
greetings
If you're on the STAR inbound to a point speed 300 Knts and you will be crossing a POINT at the desired FL:
"Instruction" : Speed 250 kts ==> You apply the instruction 250 kts (readback).
Of course you can tell the controller Reducing 250, unable to comply with altitude restriction blablabla.
Don't think about reducing "after" the point ... just do it when instructed. This will keep you out of problems. If there is a problem with the ALTITUDE, the controller will (hopefully) see this on radar and take the necessary action (if needed).
The instruction to reduce (especially in EBBU) is only given when needed. For seraration purposes
greetings
