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Radar Headings From VOR - Question  
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Posted (9 years 1 week 5 days 23 hours ago) and read 1959 times:

When air traffic say "leave holding point at 280 degrees" are they saying - tell the aircraft to head off on the 280 degree radial from the VOR or are they saying plug into the autopilot 280 degree on the heading selection. Or are they the same? I keep hearing air traffic asking for wind speeds higher up, is this because they have to give the bearing that depends on the wind speed and direction? Some controllers say "turn radar heading" isn't that the same?

I am getting confused!

J

12 replies: All unread, jump to last
 
User currently offlineFinnair MD-11 From Finland, joined Dec 1999, 158 posts, RR: 1
Reply 1, posted (9 years 1 week 5 days 23 hours ago) and read 1943 times:

Hello J,

"Leave holding point at 280 deg" means that the aircraft have to fly heading 280 after leaving the holding point. The pilot doesn't have to take account of the wind when the aircraft is being vectored. Hope this clears it up!


Finnair MD-11



MD-11
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 2, posted (9 years 1 week 5 days 23 hours ago) and read 1940 times:

Right so if they leave the VOR at 280 and there is a strong northely wind then they are going to get blown southwards this means. Therefore air traffic control will have to watch what the wind is doing to the aircraft in case it changes? I would have thought they would want all aircraft on the same radial regardless of wind to ensure safety?

User currently offlineBri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Reply 3, posted (9 years 1 week 5 days 22 hours ago) and read 1922 times:

If they're leaving a holding point at a certain altitude, the wind will affect them all the same. A good explanation of this was given in a recent post, I don't remember the title, but it had to do with descending to the transition area; a huge tailwind in the descent that shears at 10,000 feet to a headwind looks scary on radar because everyone below 10,000 looks like they're going to be run over, but they will all be affected by the shear boundary at 10,000, and the savvy controllers learn this. In the same way, if the true course from the holding point to some other point is 250, but there's a strong wind from the North, ATC might issue a vector to fly heading 280.


Position and hold
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 4, posted (9 years 1 week 5 days 22 hours ago) and read 1916 times:

This seems incredibly complex at a busy time, why not ask all pilots to fly down the 280 degree radial of a VOR making the autopilot correct for wind so they are all on the same path. Otherwise ATC have to work out which way aircraft are going to drift when they come out of the hold and try to work out what best heading to give. Sounds complex?

User currently offlineMandala499 From Indonesia, joined Aug 2001, 6972 posts, RR: 76
Reply 5, posted (9 years 1 week 5 days 21 hours ago) and read 1910 times:

This seems incredibly complex at a busy time, why not ask all pilots to fly down the 280 degree radial of a VOR making the autopilot correct for wind so they are all on the same path.

Not all holding points/fixes are VORs...

Now unless you're operating in a narrow corridor with milzones left and right, the ATC AND the pilots would prefer to see them all on Headings... because they'll be shifting sideways over the ground due to the wind at the same rate and using the same moving "fluid" to get their velocity readings...

Headings also give the controller the flexibility to make a plane leave the hold before the holding fix...

It's just a matter of practice I guess... and a matter of adapting to the situation, whether your a pilot or an ATCO...

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 6, posted (9 years 1 week 5 days 21 hours ago) and read 1904 times:

Ok I see, isn't there anyway for aircraft to data link to air traffic control so they can see the wind arrow and speed on their terminals? Having to ask all the time when the wind is changeable must be annoying, uses up airtime as well? I would have still thought having to watch which way aircraft drift just adds stress to an already busy night on air traffic and it would be much easier to have them going along the same spike/radial - but I suppose if holding points are not around a VOR then it would be tricky....so understand your point...

Another question is what mode are the pilots in when doing the hold - surely if they use the heading method they will drift with the wind so the whole stack will start moving?

[Edited 2005-12-16 19:03:58]

User currently offlineMandala499 From Indonesia, joined Aug 2001, 6972 posts, RR: 76
Reply 7, posted (9 years 1 week 5 days 21 hours ago) and read 1894 times:

You can display the wind (where the aircraft is) and your actual track on a lot of EFIS equipped aircraft (for navigational purposes, not for tactical avoidance of traffic). However, not all planes give you the ability to follow a track heading (besides the normal VOR radial)...

Having to ask all the time when the wind is changeable must be annoying, uses up airtime as well?

Why is there a need? The general wind direction? Pull it out of the ATIS... if you want a wind check, ask the Tower on finals...

When the ATC asks for an aircraft to leave a Holding Fix, he'll give the heading in 10 degree or 5 degree increments... if the wind changes for runway 27L/R at LHR, the wind changes from 220/10kts to 240/15kts, that wont affect the vectoring much... If it's say from 190/15kts to 350/15kts, unless the ATC was going to squeeze the traffic in to intercept the localizer right on the glideslope at a given altitude, then it still shouldn't be a problem... it's good practice to leave them some space to "queue" on the localizer rather than shove them on the localizer 1 - 2NM from the glideslope... Especially in busy airspace. You'll get ATC getting coronaries too often that way. Get them onto a sequencing line as safely, quickly and conveniently as possible and get the increase heart rates for abnormals!

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 8, posted (9 years 1 week 5 days 21 hours ago) and read 1892 times:

Well I have been hearing pilots pipe up and say without being asked "director I have 60 knots at 350 up here" - as if they have been programmed to tell air traffic at certain knots or direction?

User currently offlineFinnair MD-11 From Finland, joined Dec 1999, 158 posts, RR: 1
Reply 9, posted (9 years 1 week 5 days 18 hours ago) and read 1867 times:

Quoting Julesmusician (Reply 6):
Another question is what mode are the pilots in when doing the hold - surely if they use the heading method they will drift with the wind so the whole stack will start moving?

It depends on the aircraft type. You can use heading mode or fly it with the FMS (if installed) in NAV mode. During the holding pattern the pilot is responsible to correct for the wind if necessary. So that means altering the heading in x-wind situations to fly the predetermined track of the holding pattern. The holding pattern has also a predetermined outbound flying time (eg. 1 minute) so if the a/c is affected by head or tail wind the pilot should alter the outbound flying time. It depends on the pilot how precise the holding pattern will be when flying manually or in heading mode.


Finnair MD-11



MD-11
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 10, posted (9 years 1 week 5 days 17 hours ago) and read 1857 times:

Can't FMS systems using GPS correct for wind direction and speed instead of the pilot having to do manual inputs?

User currently offlineBri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Reply 11, posted (9 years 1 week 5 days 14 hours ago) and read 1834 times:

I don't know about FMSes, but any handheld GPS can help maintain a track. It's because they show you both heading and course. Of course, if you can see the ground, and have the magnetic direction from your present position to a landmark (i.e., you can see a road that goes North-South), you can also use this information. Once you know the difference between your heading and course, you can use it to compute the crosswind component. Airliners in a holding pattern are too high above the ground to do ground reference maneuvers, but as a VFR pilot, I do them all the time. GPS provides similar information without requiring line of sight.


Position and hold
User currently offlineMandala499 From Indonesia, joined Aug 2001, 6972 posts, RR: 76
Reply 12, posted (9 years 1 week 5 days 9 hours ago) and read 1819 times:

Can't FMS systems using GPS correct for wind direction and speed instead of the pilot having to do manual inputs?

Well, FMCs can do that already if you're talking about going from A to B. On holds FMCs can command those adjustments too.

Theoretically *and practically, depending on traffic* you can fly a whole route just by the FMS and autopilot (with manual take off and autoland)... BUT, in many times it's faster if the ATC gives you a short cut, cutting a significant proportion of your STAR and then then adjusting your vertical track (yes V/S is till being used) so as not to make the pax at the back puke with the VNAV trying to chase the shortcut path... or the lateral deviations...

There is no single method to fly, and there is no single method to control an airspace's traffic flow. Computers are there to do the mundane routine tasks, the human brain is there to monitor trends and take adaptive steps according to the situation.

With regards to HDG vs TRK, there are those who prefer the use of HDG and those who prefer TRK... in the end, it depends on what the controller want to use.

As to "director I have 60 knots at 350 up here" - as if they have been programmed to tell air traffic at certain knots or direction?", it's just a pilot reporting a condition that in his experience can cause concern to the situation (including Air Traffic Flow Management).

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
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