taxiing around the big iron

FORANE

FORANE

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FORANE
We all learn about wingtip vortices but what about jet blast?

How much separation do you want when taxiing around the big boys when you are in a small general aviation aircraft?
 
Good question. Following this.
 
Jet blast will ruin your day in a small airplane, in fact, prop wash from a large prop plane will mess you up too. Stay out of direct line with the business end of these AC.
 
PaulS said:
Jet blast will ruin your day in a small airplane, in fact, prop wash from a large prop plane will mess you up too. Stay out of direct line with the business end of these AC.
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Sometimes airport geometry can play havoc with your best intentions. We had a NOAA C-130 setting in the run-up area with several 172s taxiing out. Because of the arrangement, the 130 prop wash was pointed right at the taxiway. Tower did real good and called the C-130 to say hey, keep the prop speed down. I think all of us students in the 172s were glad they were rentals and still cringing while watching the C-130... This was at BJC many years ago. About the only thing the C-130 said is that they had to sit there while they tried to fix their sat phone...
 
a couple days ago I put a deposit on the purchase of a lancair 4p that I thought was just a nose gear collapse. then I found this:
http://www.kathrynsreport.com/2018/04/lancair-iv-p-c-gsqq-accident-occurred.html?m=1
The pilot stated he was 200-300 feet behind a 737...

I have cancelled the purchase of the plane. but the question remains, how far away should we be? I would have thought 200+ feet is a gracious plenty.
 
long-neck-reaction.jpg
 
Time and distance are your friend for vortices and jet blast/prop/rotor wash. The bigger the appliance making those things are, the more you need.

Rule of thumb: if you think it’s long enough/far enough away, re-read your insurance policy and balance the checkbook to see if you want to take the risk. By the time you’ve done that, you’ll probably be clear.
 
Not sure the exact distance but if they are shaking my plane and I can smell jet fuel I know I’m too close
 
I have always felt OK getting no closer than 300' to large jet aircraft. So far I have never had a problem. It sounds like the 737 was undergoing maintenance/testing so was probably more of a hazard than usual...
 
FORANE said:
I would have thought 200+ feet is a gracious plenty.
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Chances are that if the cowling was off those engines were not just at idle

I usually stay about two to three equivalent airplane lengths behind. And that has worked for me so far. So for a Gulfstream I stay two Gulfstream behind. For a 737 two to three 737s behind, etc. Thinking about it now, that probably works out to around 300 feet.. which incidentally is in line with the what the poster above said and I haven't had any issues doing that to date
 
We had a Cessna 150 flipped over by a C-130 at Wilmington a bunch of years back. This was even after the pilot coordinated with the pilot of the C-130 not to run up the engines until he had finished passing behind.
 
Ground at my airport told me I would be behind an RJ and to give it plenty of room. I opted for an intersection take off and got out before they got to the end. So "plenty of room" is the correct distance as told to me by ATC.
 
FORANE said:
We all learn about wingtip vortices but what about jet blast?

How much separation do you want when taxiing around the big boys when you are in a small general aviation aircraft?
Click to expand...
No real exact numbers for me. The bigger the plane the further back I stay. If I'm the least bit concerned I will ask ground to inform the large jet that he has a little FLiB behind him. Especially now days with a lot of these guys taxiing around on one engine. The amount of thrust they have to use on the one to get going can be much higher. Helo's can be very problematic as well.
 
Clinging around the big iron has its own risks:
 
flyingron said:
We had a Cessna 150 flipped over by a C-130 at Wilmington a bunch of years back. This was even after the pilot coordinated with the pilot of the C-130 not to run up the engines until he had finished passing behind.
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The rental -150 from my airport was flipped over by a UH-60 taking off last year. Only good for parts now...
 
We are told that there can be 100+ knot jet blast 300-500 or more feet behind us. With breakaway thrust (thrust to start the airplane moving from a stopped position) it can be dangerous 600-900 feet behind us. That is from an MD-11, a B-747, B-767 or any similar sized airplane would be about the same.
jetblast.jpg
 
I was based at IAD and watched a 172 scooting sideways an taxiway Z (well it was probably W2, back then when the taxiways had sane nomenclature before some FAA yahoo redesignated them in the name of foolish consistency) when being blown by a Fedex DC-8 parked on the cargo ramp.

The question I had was that I was well aware of jet blast, but when a 767 is breathing down your neck on the taxiway, how much do those engines suck?
 
flyingron said:
I was based at IAD and watched a 172 scooting sideways an taxiway Z (well it was probably W2, back then when the taxiways had sane nomenclature before some FAA yahoo redesignated them in the name of foolish consistency) when being blown by a Fedex DC-8 parked on the cargo ramp.

The question I had was that I was well aware of jet blast, but when a 767 is breathing down your neck on the taxiway, how much do those engines suck?
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Maybe a UPS DC-8??? FedEx never operated DC-8s.
 
The idle thrust danger zone behind our single engine jets at work is about 300 feet aft and cones out to about 100 feet off centerline. Going to full AB, then it’s closer to 1000 feet aft and 500 foot off centerline.
 
You need to be aware of inclines. If there is an upslope it requires a significant increase in thrust to power the big jet over the hill.
Also more power to get them moving from a stop.

Common sense stuff.
 
denverpilot said:
With my STOL kit you could launch me 300’ behind your airplane. Ha. :)
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B7D85F95-D662-4498-9422-8E3C3AFECD14.jpeg
You can actually use a heck of a lot less power hovering also. Little turbulent and smelly but 150-200 ft is a good sweet spot. ;)
 
FORANE said:
We all learn about wingtip vortices but what about jet blast?

How much separation do you want when taxiing around the big boys when you are in a small general aviation aircraft?
Click to expand...

When I was a young and foolish CFI I had a student in a 150 taxi behind a 737 that was on a stub-taxiway waiting for clearance into position. In retrospect, I am sure that the jet crew never saw us. Got the prop and the left wingtip (and a lesson I will never forget).

Bob
 
Ryanb said:
I’ve heard those Blackhawks throw off some nasty wake turbulence.
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Yeah, hovered past an MI-17 once and blew its clamshell doors against the fuselage. Broke the hinges and dented the fuse all up. :eek: Felt horrible.

No match for a C-17 jet blast though. Seen Black Hawks tossed around like a toy while hovering behind heavies. I’ve gotten rocked just ground taxiing broadside behind a C-130 powering up.
 
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The only place I've taxied where I had to think about this was at Kona. And the taxiway was far enough from the gates that it really wasn't an issue. Sure is something to think about, however.
 
I remember landing on 19L at KSNA, with a DC-9 between the runways holding short for 19R. It was interesting for a couple of seconds ...

Just a few weeks ago I was taxiing to my hangar at KGYR, alongside the fence separating the taxi lane from an airliner refurb facility. A 737 was parked with its tail to the fence. As I taxied closer I could hear a jet engine. I stopped, made a U-turn and went the long way around. When I parked at my hangar I walked over and saw that it was just the 737's APU in operation. Still, I wasn't about to take any chances.
 
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