ATC Rules of Thumb
 

G'day all you ATCO's,

Can you guys please advise a lowly pilot of any rules of thumb as to:

1) how you do Mach number separation? ie any rules about if 2 aircraft are stacked on top of each other, if you issue a difference of say M0.05 (so one at M0.8 and other at M0.75), it will take them X minutes to be Y Nms apart?

2) in this case would you consider using vectors to separate? or is speeed control preferred in the cruise?

3) any rules of thumb for separation in terms of in the approach phase, a difference of X knots between two aircraft starting together at the same point will mean that in Y minutes they will be Z Nms apart?

Just curious thats all.

M.01 is about 6 knots; so .05 less should give you 30kts, rule of thumb, half a mile a minute...

Works fine on cruise, descent is effectively useless using mach numbers; can work but not very 'control affective' due to the transition to IAS; different levels for different types and companies, crews... etc.

IAS works well below FL250 generally speaking.

It would totally depend on what you needed and how much time/airspace you had to deal with. 200 miles, slow down works great, 50 miles, almost a must vector scenario... My job is to space for Approach, i.e. arrivals, we need to put them across the fence at 12-15 miles gaps; I have 35 miles (80-45 Sydney) to achieve this, so it's vector city (when I'm not holding) in my part of the world; although some space is achieved by outers for jets, I "blend" in the turbo props...

120 miles to touch, 250IAS vs 300IAS will give you about two minutes at the threashold... But I'm no flow.... For me it's space by vectoring and match speeds, far less to worry about; and probably more accurate.

I used "rules of thumb" extensively as a procedural area controller abroad long ago. In the UK I always worked in an approach radar environment where you can se what's happening and experience tells you what to do so "rules of thumb" don't come into play..

The only rule you need at the end of the shift is the NCD rule.

The only rule of thumb I use is if you can fit your thumb between them then they are separated.

Cougar.
Are you asking mach no. technique? That is an actual standard in procedural (non-radar) separation. For a difference of .05M, you need 6 minutes (faster ahead, obviously) at the same level.
If you are in a radar environment (to be able to vector), you wouldn't be using MNT. But you might use mach no. for flow/sequencing purposes.
About the only rule of thumb that I can think of in the app phase; if you have 2 perfectly spaced and you want to keep it that way, reduce the second one 10kts IAS slower than the front one (the higher a/c will ground out slightly faster). It gets complicated between different types (A330/340 get down low earlier).

These rules have been posted before, and can serve as "good rules of thumb" for flow control.

Rules for successful flow control

1. Don’t trust pilots
2. Don’t trust sector controllers
3. Don’t trust tower controllers
4. Don’t trust anyone else
5. Develop a thick skin
6. Never back a Twin Otter to beat anything, even another Twin Otter
7. Never worry about departures, they are the tower's problem
8. Pray that the management pilots have good FOs
9. Computer Derived Threshold Times will be accurate only if the captain throws the computer out the storm window as he overflies the threshold in the go-round after being too intimate with the aircraft in front
10. All pilots think that they should be Number 1
11. Cardboard Bandeirantes can be used to hide unexplained gaps in the sequence
12. Unless they build more runways the maximum number of aircraft that can land at an airport in a given time will remain the same, despite the wetdreams of airline schedulers
13. Have faith in your own ability, no-one else does
14. Same money, right or wrong
15. If you believe the tower controller who says that the runway works will be finished prior to the start of the next sequence, you deserve all you get
16. Your are only as good as your last sequence
17. If your last sequence was not good, see above
18. Keep slipping the odd joke to the approach controllers, it keeps their mind off what is coming up
19. One day you will get a trainee who merely triples your workload
20. Never sit in approach and work your own sequence
21. Always keep a false nose or wig in the car, an angry mob waiting outside the carpark is not a pretty sight
22. The flow is never wrong, The flow is merely acting on information that may now be superseded

sep

I reckon there are so many ways to skin a cat in this game, that I could give the ways I do it, and 90% of the controllers on here may disagree with parts of what I say. But the thing is if it works for me then thats ok. The beauty of this job. I suppose my one rule of thumb is you can make anything work, it just depends how hard you want to work.

Oh and the old, "there for the grace of god go you or I" and my favourite and most pertinent in this part of the world, the Golden rule.... He who has the gold makes the rules (thanks Ron King).

Rule of thumb Number 1:

"If you close your eyes, it makes it all better!"

Rule of thumb Number 2:

"If Tobzalp says it will work, see rule 1................"

When you ask a pilot what his speed is, don`t believe him!

Don`t use speed control to achieve separation, only use it to maintain separation.

Why worry about the thumb - use the index finger - you can handle more aircraft then!

The only rule you have to worry about is the ''work to rule', because it never works - the boss always rules and he is never right in any case - do it any way you want to as long as you do it my way

Add to the basic rules:

23. Slot time: The only time the aircraft will not be there