Happens quite regularly in Zürich that the approach controller asks me “what’s your speed”.
I’m wondering what exactly they want to know or how I can best help them. So far I just say: “my current speed is xyz knots indicated.” That usually ends the thread.
Obviously, it has to do with them wanting to sequence me in between jets.
But still: what is the most helpful reply here? I assume they only think in knots IAS. But do they want: Current speed, maximum possible speed? In level flight? In the descent? Minimum speed?
Max final approach speed on the ILS until x miles final is usually another question I get, but that’s clear and also usually gets promoted at a later point in time.
Yes, of course, they always want IAS.
In theory, the question is as clear and means what it says. They want your current speed. Remember they can‘t see IAS, but speed restrictions are given in IAS. So, to get a picture, and to know which number to say, they have to ask for your speed first.
However, it depends a bit on where in the approach they ask. If it‘s in the initial approach, then just say your current speed. But if you are descending at a high speed and about to level off, it might make sense to say something like “currently xxx, and max level speed is xxx“. When already on final, then you could say „presently xxx, and we can do up to xxx until 5 mile final if you need“. They are normally not interested in your speed after that point, as they know you‘ll have to slow down eventually. Just make sure you don‘t give them more than what you are comfortable with. Depends a bit on VMC vs. low IMC, too.
But I agree they sometimes don‘t make it clear what exactly they want to know, and then they have to live with whatever answer they get.
To elaborate a little bit, there are standard speeds published for most approaches. Typical speeds for a standard ILS are 210 level until LOC intercept, then 180 to 6 or even 4.
Since your are obviously not meeting the expected schedule, they enquire about your speed in order to re-arrange the sequence. As Boscomantico states, my typical answer would be „180 able to 2 miles“ (disclaimer, this is the limit on a 3° for my ship, better check your data). That piece of data will complete their picture… hopefully.
In Croatia they usually ask you what speed you are able to maintain until certain distance or point.
The only time I’m asked about my speed is when they’ve got something fast behind me and I’m slower than they planned for and it’s catching me.
You were probably a little slower than they allowed for, otherwise they wouldn’t have asked, after all they can actually see you on radar.
>> You were probably a little slower than they allowed for, otherwise they wouldn’t have asked, after all they can actually see you on radar.
I don’t think that’s the case. The other day I was flying at a constant speed, which was even a bit higher than flight planned speed. Still, they asked me.
And yes, in a SEP I’m obviously always slower than the jets in an approach, except on the glide slope, where I have to slow down for them. Given the traffic volume in Zurich, there is always something faster behind me :)
HBadger wrote:
Happens quite regularly in Zürich that the approach controller asks me “what’s your speed”.
1. They want to know what they ask eg. “what is your current IAS”. Your reply as posted is adequate and correct. No need to assume anything else from ATC, they will instruct you if they deem necessary.
2. If you´re attempting to be helpful. What ATC most likely is interested in knowing, is your operational max speed until X NM before threshold, so you could advise ATC “current speed XXX kts indicated, able maximum speed (eg.) 160kts until 3NM”, this would keep the number of radio transmission down.
3. “Normal” jet speed sequencing is in line with what Dan said, although I think 180kts until 4NM is pushing it, unless you´re flying a medium turbo-prob (or some old Russian “dirty wing” jet) in VMC conditions and with a company SOP that allows for 500ft stabilized approach concept. I operationally couldn´t accept 180 until 4nm – if ATC has pushed themselves into that corner, it´s their job to get that sorted out – and they likely will (they know the local operators that are capable).
4. boscomantico wrote:
Just make sure you don‘t give them more than what you are comfortable with. Depends a bit on VMC vs. low IMC, too.
What boscomantico mentions some brilliant keywords “comfortable” “VMC vs. low IMC”. Speed (and other performance parameters) should be put in context according to the “actual on the day” operational conditions. Many other considerations such as “pilot alertness (stress, tired)”, "runway conditions (contaminated, short etc.), "Runway exit point (no point in coming in fast and miss a taxi way, only to hold up the runway for another minute taxing to the end etc.), "Winds (a solid headwind is helpful, as opposed to no wind or tailwind).. Etc. Etc. Most important – NEVER be shy of slowing everything down (not only airspeed!) – and tell ATC what you´re doing – they will work with what you need (they´re usually smarter than pilots! ;-))
boscomantico wrote:
Yes, of course, they always want IAS.
I thought they want TAS. Like in cruise when they don’t have radar (we are not used to that in Europe) and they are doing time-based separation based on self-reported positions. Like the speed that is in your flightplan (and that theoretically you are not allowed to deviate by more than X% without ATC clearance, I think X is 5?) is TAS.
That is also what my instructor told me, but once when I replied “max 165 kts” (meaning IAS), their reply was “but I see you at 180 kts now, please keep up 180 kts”. I had to explicitly reply “my maximum is 165 kts IAS, so as soon as you descend me, my TAS will go down accordingly”.
lionel wrote:
I thought they want TAS.
They want IAS. The figures are for separation and the important thing is that everyone use the same units. The flight plan speed is indeed TAS.
lionel wrote:
lionel10-Nov-23 17:2808
boscomantico wrote:
Yes, of course, they always want IAS.
I thought they want TAS. Like in cruise when they don’t have radar (we are not used to that in Europe) and they are doing time-based separation based on self-reported positions. Like the speed that is in your flightplan (and that theoretically you are not allowed to deviate by more than X% without ATC clearance, I think X is 5?) is TAS.That is also what my instructor told me, but once when I replied “max 165 kts” (meaning IAS), their reply was “but I see you at 180 kts now, please keep up 180 kts”. I had to explicitly reply “my maximum is 165 kts IAS, so as soon as you descend me, my TAS will go down accordingly”.
The only speed ATC references on the radio will be either IAS (in Knots) or Mach No/Point (in decimal). Never TAS or anything else. Nothing new to this.
Airborne_Again wrote:
They want IAS. The figures are for separation and the important thing is that everyone use the same units. The flight plan speed is indeed TAS.
This is a correct statement by Airborne.
Further to that – where are you going to read the TAS from in an analog aircraft? Which instrumentation indicates TAS? I do understand that fancy glass computes that instantly, but there still a large fleet of turbo props out there than do not have TAS available. Anyways. IAS in Knots is what ATC expects pilots to refer to.
