zarniwoop
Topic Author
Posts: 255
Joined: Wed Apr 27, 2005 11:43 pm

Hold At Idle Thrust

Fri Dec 09, 2005 7:58 pm

Was listening to JFK tower over the internet yesterday and noticed that when some departing planes were cleared to hold on the runway they were told to hold at "idle thrust" by ATC. Why so? What else are they going to do? Hold at take off power with the brakes on.........???
 
Tristarsteve
Posts: 3643
Joined: Tue Nov 22, 2005 11:04 pm

RE: Hold At Idle Thrust

Sat Dec 10, 2005 3:06 am

During icing conditions, especially when freezing fog is around, ice tends to build up on the fan blades at taxi power. So before take off the engines are run up to 70% to shed the ice off the fan blades before setting take off power. This is very noticeable here at ARN where we have a lot of SAS MD80 who practise this. This is consequent to the crash back in 1990?. So the tower will often ask them if they intend to do run up, or immediate take off.
 
User avatar
fr8mech
Posts: 7884
Joined: Mon Sep 26, 2005 9:00 am

RE: Hold At Idle Thrust

Sat Dec 10, 2005 5:19 am

Which runway(s) in use?

Ice could be the issue. At low power settings, the bleed air system may not produce enough air or hot enough air to adequately run the engine anti-ice system. So, the engine are run at a higher setting to produce the necessary results.

Another possibility is that the departure end of the runway in use may be perpendicular to another runways threshold. Landing traffic could be adversely affected by an engine running at higher power settings. Not very likely since it would mean aircraft landing and departing 90 degrees apart, but in the era of noise abatement, who knows?
When seconds count...the police are minutes away.
Unless it's expressly prohibited, it's allowed.
You are not entitled to a public safe space.
Ego Bibere Capulus, Ut Aliis Sit Vivere
 
Mir
Posts: 19491
Joined: Mon Jan 05, 2004 3:55 am

RE: Hold At Idle Thrust

Sat Dec 10, 2005 10:14 am

JFK tells traffic in position on 31L to hold at idle thrust when traffic is landing on 4R (traffic landing on 4R passes quite close behind the planes on 31L).

This generally happens in the early morning when the 4s have been in use overnight, and the 31s (which I believe have more capacity) are starting to be used.

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
A300605R
Posts: 124
Joined: Wed Nov 16, 2005 7:11 am

RE: Hold At Idle Thrust

Sun Dec 11, 2005 3:03 am

Quote:
Hold at take off power with the brakes on.........???

I've seen an Aer Lingus B735 at FRA holding on 25L with take off thrust set for about two or three minutes. Dried up the wet runway behind and made a great sound as well...
300 319 320 321 332 733 734 735 738 753 763 F27 M83
 
SlamClick
Posts: 9576
Joined: Sun Nov 23, 2003 7:09 am

RE: Hold At Idle Thrust

Sun Dec 11, 2005 3:31 am

Quoting Zarniwoop (Thread starter):
Hold at take off power with the brakes on.........???

Well, if my engines will make my three hundred and fifty thousand pound airplane go five hundred miles per hour how much of my thrust would it take to make your two thousand pound Cessna go two hundred miles per hour upside down and backwards over the airport fence?

Even idle comes pretty close to that figure.

"Hear that captain? An ELT - and nearby too!"
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
User avatar
Starlionblue
Posts: 19643
Joined: Fri Feb 27, 2004 9:54 pm

RE: Hold At Idle Thrust

Sun Dec 11, 2005 11:47 am

Quoting TristarSteve (Reply 1):
So before take off the engines are run up to 70% to shed the ice off the fan blades before setting take off power. This is very noticeable here at ARN where we have a lot of SAS MD80 who practise this. This is consequent to the crash back in 1990?.

The Gottr�ra crash was caused by sheets of ice detaching from the wings and being sucked into the engines on takeoff, not icing in the engines themselves. Icing in the engines is different. The running up of engines before takeoff will not affect wing icing.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
2H4
Posts: 7960
Joined: Tue Oct 19, 2004 11:11 pm

RE: Hold At Idle Thrust

Sun Dec 11, 2005 12:18 pm



During especially foggy conditions, pilots have been known to strategically position themselves near the runway transmissiometers, select higher-than-idle power settings, and enjoy their on-time departures.




2H4


Intentionally Left Blank
 
Dakar
Posts: 70
Joined: Wed Nov 16, 2005 5:11 am

RE: Hold At Idle Thrust

Sun Dec 11, 2005 3:30 pm

Not to hijack the thread, but what website did you use to listen to internet ATC communications?

Thanks, Nick
 
Mir
Posts: 19491
Joined: Mon Jan 05, 2004 3:55 am

RE: Hold At Idle Thrust

Sun Dec 11, 2005 4:52 pm

www.liveatc.net has a good JFK feed.

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
zarniwoop
Topic Author
Posts: 255
Joined: Wed Apr 27, 2005 11:43 pm

RE: Hold At Idle Thrust

Sun Dec 11, 2005 10:44 pm

Thanks for your replies everyone!

Quoting Mir (Reply 3):
JFK tells traffic in position on 31L to hold at idle thrust when traffic is landing on 4R (traffic landing on 4R passes quite close behind the planes on 31L).

This generally happens in the early morning when the 4s have been in use overnight, and the 31s (which I believe have more capacity) are starting to be used.

-Mir

Thats exactly the situation when i was listening

Quoting Mir (Reply 9):
www.liveatc.net has a good JFK feed.

-Mir


Thats the site I was using to listen to the JFK tower.....
 
SlamClick
Posts: 9576
Joined: Sun Nov 23, 2003 7:09 am

RE: Hold At Idle Thrust

Mon Dec 12, 2005 12:43 am

Quoting 2H4 (Reply 7):
During especially foggy conditions, pilots have been known to strategically position themselves near the runway transmissiometers, select higher-than-idle power settings, and enjoy their on-time departures.

Now that is just a rumor that got started by ATC asking us not to do that anymore.
 Wink
Happiness is not seeing another trite Ste. Maarten photo all week long.

Who is online

Users browsing this forum: No registered users and 18 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos