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Expected Approach Times explained.

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Expected Approach Times explained.

Old 20th Jun 2009, 12:03
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Expected Approach Times explained.

Following the recent hullabaloo about aircraft landing on fumes I thought an explanation of certain terms would be advantageous to all concerned. Keep in mind that the following is straight from ICAO PANS-ATM (Doc 4444).
Expected approach time. The time at which ATC expects that an arriving aircraft, following a delay, will leave the holding fix to complete its approach for a landing.

Note.— The actual time of leaving the holding fix will depend upon the approach clearance.
6.5.8 Onward clearance time

In the event an aircraft is held en route or at a location or aid other than the initial approach fix, the aircraft concerned shall, as soon as practicable, be given an expected onward clearance time from the holding fix. The aircraft shall also be advised if further holding at a subsequent holding fix is expected.

Note.— “Onward clearance time” is the time at which an aircraft can expect to leave the fix at which it is being held.
Take special note of the following: ”…or aid other than the initial approach fix,…” Now I may not be the world’s smartest person, but there is no way in hell that Desdi and Bubin are Initial Approach Fixes.

Recently a lot of pilots and airlines have been screaming for EATs and ATCOs at the UAE ACC have been instructed to issue EATs to all aircraft expecting a delay of twenty minutes or more. The idea behind this instruction is sound but the application thereof has absolutely no purpose.

Pilots want EATs so they can plan their fuel management but the truth is that UAE ACC can not issue EATs. This can only be done by an Approach unit for the simple reason that ACC can’t possibly know what is going to happen to the aircraft between the time it leaves the Desdi/Bubin en-route hold, until the time it completes the approach and land. From DESDI to touchdown on Rwy30 is about fifty nautical miles and a hell of a lot can happen in between.

What pilots are actually given when they enter the D/B holds are OCTs (Onward Clearance Times) and not EATs. If you therefore think that you can complete the approach and land at your EAT, you are sorely mistaken as another fifteen to twenty minutes can elapse before you get close to touchdown. Add another XX minutes if you execute a missed approach.

The correct application would be a hold created at the initial approach fix where DXB APP would hold traffic. Once this hold is full traffic will be held en-route at Desdi and Bubin.

Therefore a word of caution. Take any EAT you receive from UAE ACC with a pinch of salt, simply because it isn’t one.
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Old 20th Jun 2009, 15:17
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Hi BlueSky,

thanks for the info, but i guess most guys are going on the info contained in the UAE GCAA AIC, "Aeroplanes inbound to the UAE with fuel reserves approaching minimum". The one i have is dated 4th Oct 2006.

It has no mention of Onward clearance time, only EAT that will be passed by a controller when delay greater than 20 mins.
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Old 21st Jun 2009, 16:55
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Bluesky ... with all due respect. Wouldn't it be a great idea if AUH and DXB would start talking to each other? I saw better coordination between Zagreb and Belgrade while they were at war in the early nineties. God, I hope TCAS IV makes ground based ATC and its politics redundant.
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Old 21st Jun 2009, 17:50
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od, I hope TCAS IV makes ground based ATC and its politics redundant.
In much the same way that ATCs hope that CPDLC, computerisation etc will make airborne pilots redundant, I guess. With all due respect....

Dude, I think the thread is trying point out that the UAE ACC cannot provide EATs, as envisaged by ICAO when these terms were drafted. The great Dane's magnificent ATM plan (from Copenhagen circa 1976) never foresaw holding greater than 20/30 minutes. Even with unlimited amounts of co-ord between the ACC and DXB APP, the problem of knowing how long you will be flying before actually touching down cant be fixed with his system. The lack of co-ord/politics/whatever you are trying to say is the problem with ATC is nothing of the sort. It is PURELY AND SIMPLY the incompetence of the individual in charge- the great DANE. Although he isnt flying so high these days, he still has the locals bluffed into thinking he knows it all. He just doesn't have the experience or management skills to design an efficient system. He steadfastly refuses to copy the LHR system (close in holds- the bottom of which are controlled by approach), or take any advice on the matter. Until his masters realise that he is all bluff, bluster and BS, naught will change. If EK woke up to how much money he is costing them, he wouldn't just get fired....

Given the other thread about flying on fumes and relying on an accurate hold time- the poster (IMHO) was just trying to put things in perspective- especially if you are looking at decisions about committing when on vapour.
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Old 21st Jun 2009, 20:32
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I think the thread is trying point out that the UAE ACC cannot provide EATs

Personally not sure what she or he's trying to point out
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Old 22nd Jun 2009, 05:03
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PHAROH, an Expected Approach Time as defined and practiced (in most parts of the ICAO world) clearly states that it is the time an aircraft will leave the hold, complete the approach and land. Let's say for arguments sake that the initial approach fix is at 10nm from the threshold. That would make it about 3 minutes from leaving the hold to touch down. The PIC would factor these 3-4 minutes into his planning and then make a decision whether to stay or go somewhere else.

Picture this. Pilot Bob flies into DXB for the first time in his new Gulfstream 650. He gets cleared to the Desdi hold and given an EAT of 2100. He calculates his figures according to ICAO’s explanation of an EAT, but unbeknownst to him, the EAT he was given is utter bull. So come 2100 (his EAT) he gets cleared on the arrival for Rwy30. From Desdi to abeam the field is about 40nm, plus 20 for the downwind, plus 5 for the base turn and another 20 down the LLZ. What should have been a 10nm ride down the GS is now an 85nm trip through the TMA, without extra vectoring that is. At 200kts this bit would take 25 minutes instead of the 3 minutes from the IAF. Established on a 4nm final a tug crosses the landing runway and the TWR orders Pilot Bob to do a go-around. Now his fcuked.

However, if Bob was informed that his OCT was 2100 and that he would start the arrival at that time he could have made an informed decision and divert to Abu Dhabi. Instead he is floating in the Persian Gulf clinging to a blow-up sheep he stole from his Aussie cousin. Take this scenario and apply it to all aircraft holding for DXB and the likelihood of it happening is not so far-fetched.

Rant on. The GCAA is happily going along with this because RJ said it must be so. Therefore it is gospel. Amen. And not a single soul has the ability or the courage to call this guy the charlatan that he is. I will gladly write a letter to him regarding this, ten seconds after I win the El Gordo. Rant off.

I am pointing out that the information pilots receive as to their expected delay is a fabrication and has no basis in truth. How would you feel if we lied to you about the RVR readings for a fogged in runway? The guys flying into DXB regularly probably knows this but the assumption of knowledge is a dangerous thing.
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Old 22nd Jun 2009, 05:39
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Essentially what is apparent from this thread is that the ATM procedures/ airspace structure and the EK fuel policy are not compatible with regard to “commit to destination” in DXB. As Ferris says and as many of us have experienced the time airborne from leaving DESDI/BUBIN is indeterminable by ACC and the pilots.

Until a solution comes down from on high we all have to do our best to mitigate the dangers. EK captains should use their experience and authority to carry additional fuel at the times they need it (peak arrival periods) so that they have at least 20 minutes contingency. Dubai approach controllers could help out a lot by providing number in sequence or better still approximate track miles to touch down on first contact.

Blue Sky and other ATC folks thanks for taking the time to post. Dialogue like this is the only way that end-users can understand the restrictions that each work within and can only be to the benefit of all.

Ferris, please don’t lump M5.5 in with us professionals he is an armchair “expert” who likes to pronounce on matters he has very little knowledge of and then does so without much tact.
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Old 22nd Jun 2009, 07:39
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I saw better coordination between Zagreb and Belgrade while they were at war in the early nineties.
There you go, Nato E-3As are the solution...

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Old 22nd Jun 2009, 17:48
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Let me try and put things into perspective for you guys. You can cite all the ICAO references you want, but the following is a reality check:

Busy night, DESDI and BUBIN holds full. DXB has one approach controller, he feeds one director. One landing runway. You need the aircraft to exit each hold 20 miles in trail in order to have them land 5 miles apart. Therefore an aircraft can exit each hold every 5 min. (250 kts = 4 miles/min)

The guys working the holds are in Abu Dhabi Center. One controller each side, but they're also busy working traffic entering the holds, overflying, sidestepping into Sharja, etc etc. Doubtful that they have time to calculate a nice EAC time for each aircraft while you're still 20 min from BUBIN, although that would be nice, now wouldn't it. They're just too busy. ALSO. in the interest of fairness and efficiency, if traffic becomes 'lop-sided' (say light at DESDI and very heavy at BUBIN) we at DXB might call up and say "OK, space them 30 at DESDI and 10 at BUBIN, at which point all the EAC times go out the window. Even an overshoot causes extended vectors for all concerned, there goes your ETA! And because 80% of the traffic is heavies, you can't jam them like back home, wake turbulence separation must be respected.

Guess the point is we're quite low-tech, relying on some very good people to make it all work. We do not have some of the fancy flight management software available in other places. Another yet another factor is that a very high percentage of traffic here is long haul, where fuel is critical, thus this discussion.

Hope this helps a bit.
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Old 23rd Jun 2009, 06:12
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The 1 controller each side isn't quite correct if the sectors are manned properly there are two dedicated enroute/area arrivals sectors; East (Bubin) and West (Desdi).
UAE ('Emirates'... god forbid ) ACC now has a holding window function with drop down menus so that the controller or his/her planner (assisting controller) can easily select an EAT. For example if DB App wants 20Nm you simply add 4mins to the Desdi/Bubin time of the preceding aircraft (the hold menu contain original est as well as the drop down for the EAT) thereafter you add 4 min to each subsequent Est (sometimes a minute extra allowing for slow turners, pilots who can't tell time or our bad vectoring ).
There should be no excuse for not being provided an EAT unless it is due to runway closure for no visibility or an airport emergency. If the UAE hasn't given you one ask for it, as far as I am concerned and I instruct my trainees this, pilots are entitled to be told the expected/estimated length of any delay.
Yes it says EAT because one of our former glorious leaders mandated the use of the term in our local instruction manual rather than the more appropriate Onwards Clearance Time (OCT).

Ultimately as it has been said many times before dedicated flow control is needed for DXB and pretty soon AUH, but chaps we are in the ME and things don't happen as you would expect in the west.
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Old 23rd Jun 2009, 07:00
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So does everyone (except our Viking friend) agree? Dubai needs close in holding a la Heathrow - yesterday! Surely to God there's someone out there in a position to tell Sheikh Ahmed how much this current imbecilic system is costing him. (Hint to TCAS' and Ed's secretaries - highlight that last comment before you put tomorrow morning's "Pprune-pertinent-posts" on their desks.)

The only way a change will ever be sold to the Powers That Be is as a cost saving, and this one would be an enormous cost saving.
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