View Full Version : Dallas Bump???

26th Jun 2006, 11:35
Could somebody please explain Dallas Bump.

26th Jun 2006, 11:50

When an aeroplane climbing rapidly is due to level off below another aeroplane, and causes a nuisance TCAS warning despite there being no danger, but due to the rate of climb and rapid closure, still generates an RA.

26th Jun 2006, 13:06
Sounds more like the sort of "Yahoooooo, ride 'em cowboy!" that you might hear at the local rodeo...:}

gas path
26th Jun 2006, 13:31
Dallas Bump? :confused: We have a 'Denver Bump' but that was slightly different. 'Twas a EEC 'throttle push' to allow the normally asthmatic GE90 to get out of KDEN:} :suspect:

26th Jun 2006, 13:53
It happened to me. I call it the 'Dayne Bump' following an encounter with a Learjet near Manchester. I think the other guy was riding a stallion!

27th Jun 2006, 12:27
Dallas/Denver or just simply BUMP,

'Tis a term used when a little extra oomph needs to be supplied to get the a/c out of (usually) hot and high airfields. I know it is fitted to GE90, V2500 and I think some operators CFM56's.

What it does is to provide extra cooling to the engine casing via the active turbine clearance control system. This further reduces the tip clearance and thus tip losses, so increasing engine efficiency and power for a given throttle position.

The trouble is that it reduces the clearance to such an extent that tip rub takes place so in the long term it actually degrades the engine efficiency. That is why a bump take off has to be recorded in the log because after a certain number the engine must be removed for inspection/overhaul.

Linton Chilcott
27th Jun 2006, 21:43
Cathay Pacific Rolls Royce powered 747 Classics had D4 Bump (D4 was the particular mark of the RB211 on the freighters). Occasionally used for heavy departures from HK.

28th Jun 2006, 00:10
Denver Bump:
'Tis a term used when a little extra oomph needs to be supplied to get the a/c out of (usually) hot and high airfields. I know it is fitted to GE90, V2500 and I think some operators CFM56's.

Also applies to some JT8 powered MD-80s - manually set the EPR to 2.03 (90 degree day) as opposed to the normal 1.98 max takeoff thrust. Usually only authorized domestically at KDEN, hence the name.

Dallas Bump:
The Bump-Up was also a more common event when the vertical buffers were larger.

Nice bit of reading on this Rainboe.

28th Jun 2006, 03:41
VAPilot 2004, very interesting I love this stuff :)

28th Jun 2006, 04:59
We started off with reference to TCAS and ended up with engines :):)

We have the option of using a TAKEOFF THRUST BUMP... Its just another rating (TO-B, I believe), i have never heard of it referred to as "airport name-bump"...


28th Jun 2006, 06:17
Thanks for that I downloaded the PDF, It explains Dallas Bump well together with a diagram.

28th Jun 2006, 14:54
Never knew there were so many lumps and bumps in aviation!.......But the nicest of them all are the 'lady bumps'.

OK OK I'm banned from Tech Log for 3 days!

28th Jun 2006, 15:55
And, let us not forget, as long as RR RB.211 engines have been mentioned, that there is also a bump thrust available for the TriStar, both the -22B and -524B402 models.
The basic -524B02 used at SV, was interesting in that it was a derated engine already, so altho a bump thrust rating would have been useful on some occasions, one was not published...you had to write to Rolls Royce for the data.
I mentioned this to the L10 fleet manager one day and his reply was...'shhhhh, say nothing, please, we have enough problems with some of our pilots as it is.'

30th Jun 2006, 01:37
Ah 411A, thats like trying to get an answer out of Boeing for some of their non-sensical/non-mathematical calculations. Typical answer is " we don't have the engineering resources to answer you question " = sod off and leave us alone, like it or lump it.