No gyro approach
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No gyro approach
Call me naive but I was under the impression that when a request is made for a no-gyro approach, the controller would see your heading change straight away on his radar screen when telling you to turn left, right stop turn etc - but today the controller complained that I was failing ( well my student was ) to make rate one turns and I guess ended up heading in the wrong pre-caluclated direction. I had failed the DG on the student and requested a practice no gyro approach - so I guess you ATCO fellas are timing it all on your little watches. Rate one turns except on final when half rate one turns can be expected so the regs say - so no more than half rate one turns when tracking the inbound course once established ? What's that all about ? Another Q I have for ATC, is do you ever consider that when practice approaches are being requested and there is little traffic, do you ever condsider economy - that the student is stumping up $800 an hour for the aircraft and every time you extend the manouvering without good reason ? Not attacking you guys, but just interested.
Last edited by LeakyLucy; 18th Nov 2007 at 02:17.
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The direction of flight is determined on a radar tube by observing the trail that previous sweeps of the radar leave on the tube. A typical Approach Radar might rotate at about 15 RPM or one sweep every 4 seconds. If you turn rapidly, the controller will net be able to determine your direction of flight accurately, particularly if the aircraft is moving slowly.
The reason that rate1/2 turns may be used on final approach particularly when Precision Approach Radar is in use is that required turns are likely to be small - e.g. 3 degrees which would only take 1 second at rate 1. How quickly can you say "Turn right NOW, Stop turn NOW?"
Incidentially, when I started in ATC back in the 60's, it was not unusual to do "No Compass No Gyro" approaches using only D/F and a stopwatch. The principle was to get a couple of D/F bearings. If the second was less than the first, the airfield was on the aircraft's left & vice versa. If both bearings were identical, the airfield was either directly ahead or directly behind. In all cases a timed 30 second turn (90 deg at rate 1) would be given.
After observing the difference between the bearings, further turns left or right would be given, each one half of the previous time so that the aircraft after zig-zagging a few times ends up homing to the overhead from where a D/F let down could be commenced.
Reg Ford
The reason that rate1/2 turns may be used on final approach particularly when Precision Approach Radar is in use is that required turns are likely to be small - e.g. 3 degrees which would only take 1 second at rate 1. How quickly can you say "Turn right NOW, Stop turn NOW?"
Incidentially, when I started in ATC back in the 60's, it was not unusual to do "No Compass No Gyro" approaches using only D/F and a stopwatch. The principle was to get a couple of D/F bearings. If the second was less than the first, the airfield was on the aircraft's left & vice versa. If both bearings were identical, the airfield was either directly ahead or directly behind. In all cases a timed 30 second turn (90 deg at rate 1) would be given.
After observing the difference between the bearings, further turns left or right would be given, each one half of the previous time so that the aircraft after zig-zagging a few times ends up homing to the overhead from where a D/F let down could be commenced.
Reg Ford
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The reason that rate1/2 turns may be used on final approach particularly when Precision Approach Radar is in use is that required turns are likely to be small - e.g. 3 degrees which would only take 1 second at rate 1. How quickly can you say "Turn right NOW, Stop turn NOW?"
that's the bit missing from the text books - all clear now -
that's the bit missing from the text books - all clear now -
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What do you mean "extend the manouvering without good reason"?
No-one is going to vector you for extra track miles unless there's a good reason!
Do you mean the radar circuit is too big, or you intercept final at too long a range or....?
No-one is going to vector you for extra track miles unless there's a good reason!
Do you mean the radar circuit is too big, or you intercept final at too long a range or....?
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Well I would like to be vectored onto final asap - I'm only interested in shooting the approach for student practice. I see lots of occasions where there is little or no traffic where I'm vectored 15 or more miles out. I fly a turbine helo which aint cheap to run, and I'm just interested to see if ATC hold any regard for keeping costs down for us, whether individually or as a whole.
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If someone's on a training approach I always try to ask how long a final they want. I find that a lot of folk want to start from 10 or 15 miles & 3000' to get max benefit from each approach (& fee). At the other end I try to minimise any climbing away from the airfield to save their pennies on miles they don't need.
With regard to rate "whatever" turns, I have two points.
1. My radar goes from "somewhere else" to ac, back from ac to "somewhere else", through a modem, down a telephone line, through another modem and arrives at my screen about a week later, so anything I see has already happened.
2. In my 12 yrs of radar no two pilots' interpretations of a rate-one turn have ever been the same.
Because of the above I gauge the rate of turn early on where it's less crucial and take a slightly more cautious pattern.
I would really try not to upset a pilot over the r't cos it just makes my job even harder!
With regard to rate "whatever" turns, I have two points.
1. My radar goes from "somewhere else" to ac, back from ac to "somewhere else", through a modem, down a telephone line, through another modem and arrives at my screen about a week later, so anything I see has already happened.
2. In my 12 yrs of radar no two pilots' interpretations of a rate-one turn have ever been the same.
Because of the above I gauge the rate of turn early on where it's less crucial and take a slightly more cautious pattern.
I would really try not to upset a pilot over the r't cos it just makes my job even harder!
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OK, clarify a bit more.
You say you are vectored 15 miles out. Do you mean track miles, or onto a 15 mile final?
Normally I would vector onto an 8 mile final unless otherwise requested or there was traffic in front.
If you mean extra track miles, it might be because we will put you into a radar "circuit", like a large fixed wing circuit. This means you will be taken onto a downwind (at my airfield) 5 miles north of the airfield, which will give you a 4 mile base leg. We will generally turn you onto a closing heading to intercept the final approach track at 30 degrees.
It may be that because you are a lot more manouverable, you feel this is too large, but a jet would want the miles. You can always ask for vectors direct to an 8 mile final, or to self-position for the approach. If, as you say, there's no traffic, I doubt this would be a problem.
Finally, there could always be more traffic that you don't know about. Pilots often forget that we could be working traffic on multiple frequencies (approach/radar/director/UHF/VHF).
Does that make sense?
You say you are vectored 15 miles out. Do you mean track miles, or onto a 15 mile final?
Normally I would vector onto an 8 mile final unless otherwise requested or there was traffic in front.
If you mean extra track miles, it might be because we will put you into a radar "circuit", like a large fixed wing circuit. This means you will be taken onto a downwind (at my airfield) 5 miles north of the airfield, which will give you a 4 mile base leg. We will generally turn you onto a closing heading to intercept the final approach track at 30 degrees.
It may be that because you are a lot more manouverable, you feel this is too large, but a jet would want the miles. You can always ask for vectors direct to an 8 mile final, or to self-position for the approach. If, as you say, there's no traffic, I doubt this would be a problem.
Finally, there could always be more traffic that you don't know about. Pilots often forget that we could be working traffic on multiple frequencies (approach/radar/director/UHF/VHF).
Does that make sense?
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There's no point getting too scientific about it... although rate 1 (or .5) the only NCNG turns I would bother to time would be long turns i.e. more than 90 degrees (as much for workload management, and so I didn't forget the guy was in the turn, as anything else)... any smaller turn was done by "grabbing a handful" - a bit of experience mated with trial and error seemed to work? (with fast traffic it is easier to watch the turn on radar, slow traffic wouldn't go too far in the wrong direction before you notice).
