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How Long Does It Take F-15’s To Reach Mach 1?  
User currently offlineLenbrazil From Brazil, joined Apr 2006, 114 posts, RR: 0
Posted (8 years 3 months 4 days 7 hours ago) and read 11217 times:

How long does it take F-15’s to reach mach 1 or mach 1.5 ?

There are conflicting reports on how fast the fighters from Otis AFB that took off at 8:52 or 8:53 AM on 9/11 to intercept flights 11 (which they didn’t know had crashed) and 175 flew. The the reported speeds vary between 500 and 1200 mph [ http://www.cooperativeresearch.org/context.jsp?item=a852otisscramble ]

CTers (I’m NOT one) claim the fighters flew suspiciously slowly but the pilots said they flew supersonic. The question is why did they only reach Manhattan (coincidentally) at 9:11? 18 or 19 minutes to cover the approximately 194 miles = 613 – 647 mph average speed well below mach 1.

I think it could be due to two factors.

1) It takes time to accelerate to break the sound barrier and cruising altitude and then time to slow and come down.

Can any of you tell me about how long it would take to reach mach 1 or mach 1.2 or 1100 – 1200 mph (about mach 1.5)? About how far would they have traveled at that point?

Also I imagine conversely it would take time decelerate and a fighter would only want to be slightly faster (if at all) that the aircraft it was intercepting.

I imagine they also would have lost time/distance reaching cruise altitude and then descending again.

So one has to differentiate between top speed flown and average horizontal speed for the trip.

I know there is a 250 Kt speed limit below 10,000 feet but I saw on a USAF site that military planes have a waiver. I also know that supersonic flights are normally prohibited but some one from the air force said interceptors routinely fly supersonic ‘in appropriate situations’ (not an exact quote).

2) The fighters might not have flown the shortest distance from Otis to NYC (which basically would have had them flying over Long Island) but rather taken a slightly longer route over the Atlantic. A USAF general testified before Congress that the fighters scrambled from Langley AFB (which is NOT in Langley, VA but about 130 miles south of DC) did do so as not to fly in the busy East Coast corridor. I imagine this also might be done to avoid creating sonic booms over populated areas (would this be an issues at the altitudes they would have been flying) and possibly to reduce the risks to people on the ground if they crashed. These factors maybe related to the subsonic rule mentioned above. One site estimated such a route to be about 225 miles.
http://www.911myths.com/html/fighter_speeds.html

I am interested to here the opinion of anyone with expertise but what I would find especially valuable are links to reputable sources. Please tell me what relevant experience (if any) you have to answer my questions.

Thanks in advance,

Len

PS F-15’s are said to have top speeds of about 1850 mph but it’s my understanding this is only for new jets imperfect conditions and 1500 mph is really the upper limit.

Some CTers say standard "scramble order" to 29000 feet time is 2.5 minutes this seems impossibly fast to me.

14 replies: All unread, jump to last
 
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12135 posts, RR: 51
Reply 1, posted (8 years 3 months 4 days 7 hours ago) and read 11215 times:

Quoting Lenbrazil (Thread starter):
CTers (I’m NOT one) claim the fighters flew suspiciously slowly but the pilots said they flew supersonic. The question is why did they only reach Manhattan (coincidentally) at 9:11? 18 or 19 minutes to cover the approximately 194 miles = 613 – 647 mph average speed well below mach 1.

The MAANG F-15s were sent to intercept UA175, but were initally vectored over the water, then direct to NYC. Both F-15s accelerated to about Mach. 1.3, and were still 75 miles away when UA175 hit the WTC tower. The fighters launched from Otis ANGB about the same time as AA11 hit the WTC tower.

Quoting Lenbrazil (Thread starter):
A USAF general testified before Congress that the fighters scrambled from Langley AFB (which is NOT in Langley, VA but about 130 miles south of DC) did do so as not to fly in the busy East Coast corridor. I imagine this also might be done to avoid creating sonic booms over populated areas (would this be an issues at the altitudes they would have been flying) and possibly to reduce the risks to people on the ground if they crashed. These factors maybe related to the subsonic rule mentioned above. One site estimated such a route to be about 225 miles.

The Langley F-16s were initally vectored out over the water, also. But ATC sent them 75nm from the coast before they turned back towards the Pentagon.

At that time (the time AA crashed into the Pentagon), there was still no clear authorization to shoot down cilivan airliners. It was only after the crash at the Pentagon that VP Chaney authorized USAF to shoot. Predident Bush agreed with the Vice President, shortly after that.

But, to answer your question, a combat loaded F-15 or F-16 can exceed Mach. 1 in less than 2 minutes. But, it is not normally done because of the amount of fuel that is burned. The 2 MAANG F-15s could only hold over NYC for about 20-25 minutes before they had to recover into McQuire AFB, NJ to refuel. But, that was enough time to get other CAP fighters airborne.


User currently offlineChecksixx From United States of America, joined Mar 2005, 1088 posts, RR: 0
Reply 2, posted (8 years 3 months 4 days 4 hours ago) and read 11178 times:

Quoting KC135TopBoom (Reply 1):
The Langley F-16s were initally vectored out over the water, also. But ATC sent them 75nm from the coast before they turned back towards the Pentagon.

Okay, here's how it went down at Langley that morning.

1) The 119th had (2) jets sitting alert with (1) spare. A call came in along with the scramble order and they were basically told to get all of the armed jets in the air. (2) jets got airborne with the 3rd just a minute or two behind. Because it was a general scramble order with no specific threat/flight information, they went into a generic flight plan (standard proceedure) to await instructions. This took them out over the Atlantic to a holding area. Commercial ATC had nothing to do with this.

2) When the jets were told to head to D.C., the Pentagon had already been hit. The flight lead sent the two wingmen to altitude and he flew down the mall over the Pentagon to asses what was going on.

3) Most people don't know that the largest Russian naval exercise since the cold war was taking place off of the east coast. Initially it was thought by the pilot that maybe a cruise missile attack was underway, but once he flew over he realized that it was probably an aircraft crash. After the fly-over they escorted flights into the D.C. area.

As an aside, I know at least one fighter squadron at Langley began arming the birds on the ramp as soon as the base opened back up.

-Check


User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12135 posts, RR: 51
Reply 3, posted (8 years 3 months 3 days 12 hours ago) and read 11036 times:

Quoting Checksixx (Reply 2):
As an aside, I know at least one fighter squadron at Langley began arming the birds on the ramp as soon as the base opened back up.

Yes, actually it was the entire 1st Wing (formally the 1st TFW), getting their F-15Cs ready.


User currently offlineChecksixx From United States of America, joined Mar 2005, 1088 posts, RR: 0
Reply 4, posted (8 years 3 months 3 days 7 hours ago) and read 10988 times:

Quoting KC135TopBoom (Reply 3):
Yes, actually it was the entire 1st Wing (formally the 1st TFW), getting their F-15Cs ready.

No, it was one squadron.

-Check


User currently offlineLenbrazil From Brazil, joined Apr 2006, 114 posts, RR: 0
Reply 5, posted (8 years 3 months 3 days 3 hours ago) and read 10960 times:

Quoting Checksixx (Reply 2):
But, to answer your question, a combat loaded F-15 or F-16 can exceed Mach. 1 in less than 2 minutes. But, it is not normally done because of the amount of fuel that is burned. The 2 MAANG F-15s could only hold over NYC for about 20-25 minutes before they had to recover into McQuire AFB, NJ to refuel. But, that was enough time to get other CAP fighters airborne.

I don't know if it would make much difference but the planes that flew out of Otis were F-15A's, which from what I've read were produced between 1974 and 78. In other words they were 27 -23 years old. It is my understanding that over time their performance decreases.

To have beaten flight 175 to the towers they would had to have maintained an average speed of over 1150 mph IF they had flown a direct line.


User currently offlineLenbrazil From Brazil, joined Apr 2006, 114 posts, RR: 0
Reply 6, posted (8 years 3 months 3 days 3 hours ago) and read 10950 times:

Quoting KC135TopBoom (Reply 3):
Because it was a general scramble order with no specific threat/flight information, they went into a generic flight plan (standard proceedure) to await instructions. This took them out over the Atlantic to a holding area. Commercial ATC had nothing to do with this.

2) When the jets were told to head to D.C., the Pentagon had already been hit. The flight lead sent the two wingmen to altitude and he flew down the mall over the Pentagon to asses what was going on.

That is one thing I never understood. Of course hindsight is 20/20 and the USAF/NORAD were set up at that point to protect the US against aircraft invading its airspace. But NYC had just been attacked with hijacked jetliners and I believe they had a CAP over that city. Wouldn't the most logical thing been to have done the same over DC. Norad was informed before the fighters took off that flight 77 was heading towards DC.

http://www.cooperativeresearch.org/t...lete_911_timeline&day_of_9/11=aa77

Len


User currently offlineLenbrazil From Brazil, joined Apr 2006, 114 posts, RR: 0
Reply 7, posted (8 years 2 months 4 weeks 22 hours ago) and read 10732 times:

According to a Cape Cod Times writer who interviewed the pilots who were sent to intercept flights 11 and 175 soon after take off they were "booming* over Sandwich" [ http://911research.wtc7.net/cache/pl...d/capecodtimes082102_ithought.html ]. Sandwich, MA is about 8 miles North/Northeast of Otis AFB so that would only make sense if they used the Northeast runway (see map http://www.google.com/maps?f=q&hl=en...205&spn=0.171741,0.431213&t=h&om=1 – the ‘x’ west of Maspee is Otis’s runways ). It makes sense they would have been lined up for the NE runway for 2 reasons:
1) Their primary mission was to intercept aircraft coming into US airspace i.e. from the east.
2) The start of the NE runway (which also the end of the SW runway is close to Otis’s offices, the start of the SE runway is far from the offices – see airport diagram, note that the top is west, north is to the right http://204.108.4.16/d-tpp/0605/00894AD.PDF

This would have put them on a heading of 53.7 degrees. Lt. Col. Duffy told ABC News they were directed to JFK Airport [ http://911research.wtc7.net/cache/pe...news091102_jenningsinterviews.html ]. The heading from Otis to JFK is 249 degrees [ http://www.airnav.com/airport/KJFK - enter KFMH, the code for Otis, in the ‘Airport distance calculator’], thus they would have had to make a 164.7 degree turn over populated areas or a 195.3 turn over the Atlantic. Perhaps the turn over the sea would only been about 180 if the were going to fly offshore down Long Island but this would have added a few more miles.

This of course would have added a couple of minutes to the flight, the question is how many. Anyone want to speculate how long from break release until they were heading in the right direction and the same distance as when they started? Could they have been supersonic at that point or would that have taken longer? About how many miles would this add to the flight?

A retired USAF fighter pilot who I know from another forum who flew F-101’s and F-102’s said you’d want to be at over 20,000 before breaking the sound barrier to not cause problems on the ground and I imagine getting to that altitude would take some time too.

If any of you have military aviation experience, please let me know.

Len

*I assume the "booming" part was poetic license and/or a false assumption on the author's part because, I doubt they would have broken the sound barrier at that point (too low, too short a distance). Even if they could have reached such a high speed in such a short distance (while climbing) doing so in the wrong direction would have been counter productive.


User currently offlineLenbrazil From Brazil, joined Apr 2006, 114 posts, RR: 0
Reply 8, posted (8 years 2 months 4 weeks 21 hours ago) and read 10732 times:

Quoting KC135TopBoom (Reply 1):
The MAANG F-15s were sent to intercept UA175, but were initally vectored over the water.

Do you have a reference for that?


User currently offlineBladeLWS From United States of America, joined Dec 2005, 403 posts, RR: 0
Reply 9, posted (8 years 2 months 4 weeks 20 hours ago) and read 10716 times:

http://www.9-11commission.gov/report/911Report.pdf

User currently offlineHaveBlue From United States of America, joined Jan 2004, 2106 posts, RR: 1
Reply 10, posted (8 years 2 months 4 weeks 8 hours ago) and read 10650 times:

Thanks for the link BladLWS, extremely interesting reading.


Here Here for Severe Clear!
User currently offlineLenbrazil From Brazil, joined Apr 2006, 114 posts, RR: 0
Reply 11, posted (8 years 2 months 3 weeks 6 days 21 hours ago) and read 10592 times:

Quoting Lenbrazil (Reply 8):
Quoting KC135TopBoom (Reply 1):
The MAANG F-15s were sent to intercept UA175, but were initally vectored over the water.

Do you have a reference for that?



Quoting BladeLWS (Reply 9):
http://www.9-11commission.gov/report/911Report.pdf

The 9/11 commission didn’t say very much only “Radar data show the Otis fighters were airborne at 8:53. Lacking a target, they were vectored toward military-controlled airspace off the Long Island coast. To avoid New York area air traffic and uncertain about what to do, the fighters were brought down to military airspace to “hold as needed.” From 9:09 to 9:13, the Otis fighters stayed in this holding pattern.120”

I believe this to be in error because in contradicts what the pilots and NORAD told the press i.e. that they were vectored toward JFK but were 71 or “about 60” miles away when the South Tower was struck at 9:03 and only then sent to the holding area off Long Island because there no longer was a target. See the links from my post above and NORAD’s press release http://news.findlaw.com/hdocs/docs/terrorism/norad091101.html .

Later the report said “Radar data show that at 9:13, when the Otis fighters were about 115 miles away from the city, the fighters exited their holding pattern and set a course direct for Manhattan. They arrived at 9:25 and established a combat air patrol (CAP) over the city.136” Obviously the only way the could have been about 50 miles further away 10 minutes later is if they had flow away during the interval. Also they don't explain where the planes were between 8:53 and 9:09, if it really took them 16 minutes or so to fly the 80 - 90 miles or so to the holding area (off Montauk) the CT's are right the were flying unusually slow that would come out to an average speed of 300 mph about 100 mph below the take off speed for an F-15. I don’t think the mistake was intentional.

I think it’s possible that before the pilots were informed that they no longer had a target the were flying “off shore” to avoid civilian air traffic.

Len


User currently offlineRedFlyer From United States of America, joined Feb 2005, 4318 posts, RR: 28
Reply 12, posted (8 years 2 months 3 weeks 6 days 20 hours ago) and read 10580 times:

Quoting KC135TopBoom (Reply 1):
But, to answer your question, a combat loaded F-15 or F-16 can exceed Mach. 1 in less than 2 minutes.

Do you mean from wheels up or from some other flight aspect?

Somewhat off topic, but I remember back in the 80's when the F-20 Tigershark was being marketed (unsuccessfully), I knew a USMC pilot that said one of its performance features that was touted was its ability to go from a cold start to 30,000 feet in under 2 minutes. Of course, everthing had to be in place for this to happen (e.g., pilot strapped in, pre-flight completed, a/c positioned at runway end, etc.). And I'm assuming it included combat load since such a performance advertisement would be intended to show its interceptor capabilities.



I'm not a racist...I hate Biden, too.
User currently offlineDeltaDC9 From United States of America, joined Apr 2006, 2844 posts, RR: 4
Reply 13, posted (8 years 2 months 3 weeks 6 days 9 hours ago) and read 10527 times:

Quoting Lenbrazil (Thread starter):
CTers (I’m NOT one) claim the fighters flew suspiciously slowly but the pilots said they flew supersonic. The question is why did they only reach Manhattan (coincidentally) at 9:11? 18 or 19 minutes to cover the approximately 194 miles = 613 – 647 mph average speed well below mach 1.



Quoting KC135TopBoom (Reply 1):
But, to answer your question, a combat loaded F-15 or F-16 can exceed Mach. 1 in less than 2 minutes. But, it is not normally done because of the amount of fuel that is burned. The 2 MAANG F-15s could only hold over NYC for about 20-25 minutes before they had to recover into McQuire AFB, NJ to refuel. But, that was enough time to get other CAP fighters airborne.

You beat me to it, fuel management is important. You dont want to get there with empty tanks or slow down to meet a tanker, if tankers were there to meet. Dont know about that.

I think this may be a scenario where the F-22 with supercruise would have been quite handy, quicker on the scene because no afterburner needed to go 1.4-1.6 mach giving more hang time.



Dont take life too seriously because you will never get out of it alive - Bugs Bunny
User currently offlineLenbrazil From Brazil, joined Apr 2006, 114 posts, RR: 0
Reply 14, posted (8 years 2 months 3 weeks 6 days 2 hours ago) and read 10437 times:

Quoting RedFlyer (Reply 12):
Do you mean from wheels up or from some other flight aspect?

From wheels up and brake release, this could explain the 1 minute difference between the times cited by NORAD and the 9-11 Commision the latter based it's time on radar data which I assume would only pick up after wheels up


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