London TMA

[Jenson Button]

Folks, I have a question with regard to being vectored off the stacks that came up this week. We were asked to "tighten up our turn" to leave the stack on a heading. As the autopilot is flying the a/c, doing a very nice job of rate one turns - we can only do this by slowing down which reduces the radius of turn or manually fly beyond rate one. The latter would be a tad bit uncomfortable for the slf. Any suggestions or thoughts ??

JB

[anotherthing]

Hi JB,

It might help if you mention what airport and what stack you are referring to - different airports have different issues... you might even get an answer from the actual controller that asked you to do this.

As an LTMA area (not approach) controller I would say that there must have been a pretty good reason to ask for a tight turn. It might even be something as simple as the controller being caught out by the wind.

I appreciate that at that particular stage of the flight you would rather leave the autopilot to do its stuff than take over and hand fly it, but sometimes needs must.

As for the passengers - tightening the turn should still be a smooth manoeuvre - it's not like an avoiding action - it can be done non-aggressively. I would have thought as well that at that stage of the flight they the seatbelt sign would be illuminated.

I would hope that the request was not something that you encounter regularly as that could infer poor procedure design or poor controller technique. If it is a request that is made regularly to you when flying into the same airport, then it is worth a phone call to find out why.

Maybe you will get a definitive answer if the ATCO happens to read your thread – but a clue as to where you were operating to might help. :ok:

[Max Angle]

All jet transports have a normal ops. bank angle limit of 30 degrees autopilot or hand flying, so you are not going to get the turn tightened to any significant extent even if the pilot sheds a few knots. What does happen sometimes is the turn is done using a NAV mode rather than heading which sometimes takes a fairly lazy turn to start with so a few more degrees could be added to the turn by changing modes.

[tired-flyboy]

My tuppence worth,

It could have been that there was a gap that the approach controller was anticipating you to go into, but as the autopilot was in control you were extending out a couple of miles further than the approach chap was wanting.

so a quick 'could you tighten the turn' was just to try and get the spacing right for the sequence.

[Jenson Button]

Thanks for the replies.....

The request was made off the BNN stack for LHR.

If we use the NAV mode to exit the Hold, the FMS doesn't do a 360 turn back to the holding fix but something inbetween a rate one turn and part of the hold. Using a simple HDG mode we can achieve the tightest turn back to the fix.

I think its worth a phone call to find out from the horses mouth....

cheers folks

JB

[HEATHROW DIRECTOR]

As an ex-Heathrow controller who spent many years bringing people off BNN I would say that in most cases the holding patterns are flown fairly accurately but the odd aircraft makes a wide turn which can either make it difficult to get it back into the landing sequence or, occasionally, takes it into conflict with other traffic. I've certainly asked pilots to tighten their turns more times than I've had hot dinners so it isn't (or wasn't!) something unusual.

Confusion sometimes arises when you have just left the VOR and starting the turn outbound and the controller says "continue the right turn on to 130 degrees". It means just that... but some pilots turn back to the VOR before turning on to 130. If ATC wants that, they say "Return to BNN and leave heading, etc..".

As tired-flyboy suggests, it's to fill gaps and there are a million ways to do it! ("Knit one, perl one" as we used to say 100 years ago).

[Max Angle]

Yes but if you are in holding pattern turning outbound then a turn in the same direction to any other heading will take you back to the fix anyway most of the time, it's a 30 degree turn no matter what heading you are turning to.

[HEATHROW DIRECTOR]

Max...... Not all the time. Depends on the wind. For example, leaving BNN on the outbound turn... strong northerly wind... continuing the turn round on to, say, 120, will often take the aircraft south of BNN.

[wrecker]

What ever happened to the westcott snatch?

[Roffa]

Nothing. The opportunity for one perhaps doesn't arise as often these days but he/she/it was alive and well last week.

[Scuzi]

Jenson Button - I may have been the cause of you being asked to tighten up your turn. Due to the congestion of the airspace around that area, we (I?) sometimes run things quite tight although still well within the rules.

If it was indeed you, there was a situation where I was climbing an northbound outbound about 3-5 miles east of BNN and an aircraft which was talking to Heathrow was being vectored off the stack. The aircraft being vectored off ran a bit wider than I expected which prompted a phonecall from myself to Heathrow approach to ask that the turn be "tightened" to prevent me turning my outbound to the east into the way of the other 4 or 5 outbounds that happened to be in the way (what a surprise!).

It was all perfectly safe - just a matter of ensuring we got the 3 miles required:ok:


Wrecker - There's still plenty of snatch action to go around on Easterlies. It depends on the time of the day/month/year though :E