How Did the 9-11 Hijackers Navigate?

[cforst513]

also, they were going full throttle at the time of impact, weren't they? the second plane almost looked like it was going to miss the building entirely. if they had entered the coords and let the airplane fly itself, would it be able to get to those exact coords while turning at full throttle? also, on a different tangent, were the black boxes ever recovered, or were they destroyed? i was just curious.

 

[User546]

I should probably bring up the fact again that the documentry indicated that very quickly after taking over the airplane, the hijackers turned off the autopilot and began hand flying the airplane. From the indications of the phone calls that the F/A's were making back to home base, they were flying very erratic, and came close to losing control more then a couple times (banking well past 90-120 degrees).

Going back to the handheld GPS theory... if they were using one, it was probably like the way most of us use it. They probably dialed in direct, got the heading they needed to fly, and then flew it that way. That could explain the wobbly line on their paths to their targets. Then as they got closer to NYC, they started "visually" correcting.

Just another hypothetical to throw into the discussion....

 

[EagleRJ]

The black boxes were destroyed, but the planes' speed could be estimated by radar and video evidence.

AA11 was flying almost level down the length of Manhattan, although it was at maximum level speed (around 400 kts if I recall).

UA175 was diving at the time of impact, and most experts believe the terrorists were on the verge of losing control as they tried to avoid overflying the WTC. The plane's speed was estimated at 575 kts, or about Mach .82 at that altitude. It was so far above Vmo that the terrorists could have stressed the aircraft beyond ultimate load with just moderate control inputs.
GPS wouldn't be needed for the last few minutes of flight. The terrorists had a target that they simply had to keep centered in the windscreen. Monkeys could have done it.

 

[Makesheepnervus]

TIS,

Actually the WTC's stood out real easy, I know this because I have had a fair amount of experience flying in and out of the NY area both before and after 911, as I said earlier finding NYC presented no problem, remember, the second plane had the advantage of the smoke plume to home in on.

Having said that I think It is more likely they just programmed the FMS with the appropriate waypoints.

As EagleRJ says, "A monkey could have done it."

 

[rumpletumbler]

Those weren't planes....they were cardboard cutouts of planes taped onto cruise missles.

 

[YGBSM]

I have had a question regarding this for a long time. I understand how the pilots could have figured out x and y. Lat and long would be fairly easy to program. Handheld FMS whatever.... However z would be quite tough.

What i mean is

How could they have figured out the vertical navigation? My students blow that one all the time. Its fairly easy to overshoot or be to fast in a high performance airplane like a Commanche. I see my students do it often. In fact it happens sometimes in the 172 if I dont say anything to the student. Those bastards (may they rot in hell) didn't have the benifit of a glideslope some way to figure out how to plan for the decent.

My understanding of anything more advanced than a Conquest is very limited. But I do know that vertical nav is fairly tough even for seasoned pilots. Mostly because a 76 or the like is pretty slippery and would be hard to slow down.

Any thoughts on this one?

I have one in the form of a question.

Can you explain to me as an instructor the importance on being on speed or on profile when driving your airplane into the side of a f****** building?

 

[Bob Runday]

My question is this: Once the hijackers took control of the airplane, how did they navigate the plane from somewhere outside of Boston to two "tiny" buildings in NYC? Do you think the hijackers would've been savvy with the FMS, or did they use some other form of navigatoin?

Has anyone ever heard of an explanation how this was possibly accomplished?

Most animals have an intrinsic ability to self-navigate. They also eat there own ----. I guess that explains what they used for a snack enroute.

Oh, that reminds me, I need to be changed.

 

[FN FAL]

Those weren't planes....they were cardboard cutouts of planes taped onto cruise missles.

With chemtrail generators...grab your tin foil hats!

 

[BushwickBill]

Can you explain to me as an instructor the importance on being on speed or on profile when driving your airplane into the side of a f****** building?

Overshoot would be the keyword that you may want to spend a bit of time thinking about. As in being too high and not being able to decend in time to hit your target. Hitting the target would be fairly simple, a monkey could indeed do it. However hitting it from a starting altitude of say 18,000 feet would involve a little more brainpower.

I think one user said they were already at a low altitude when they arrived in the general area which would make it really simple.

But all this monkey talk makes me wonder: are you guys so hammered with SOP's that you cant even think for yourselves anymore?

 

[FN FAL]

But all this monkey talk makes me wonder: are you guys so hammered with SOP's that you cant even think for yourselves anymore?

I run into that stuff all the time in school. People seem to need a straightforward list of instructions to help them keep from falling outside the "box". Otherwise they wouldn't know what to do.

Some of my best college papers were done after looking at the teach's assignment and finding chinks or holes...so I could go outside the "envelope" and bring something totally different into the assignment and make it relevant. I think of those holes as license...my classmates looked at those gaps in the instructions as a vague limitation, needing clarification.

Yes, when operating large aircraft under 121, you must adhear to policy and procedure...and there's a very serious reason for it. But when you're trying to figure out what the hell some dumb ass renegades are going to do...you kind of have to step in their world or explore other correlations, if you can.

 

[YGBSM]

But all this monkey talk makes me wonder: are you guys so hammered with SOP's that you cant even think for yourselves anymore?

I'm not the one asking how to descend from 18,000 feet without navigational guidance.

 

[BushwickBill]

I'm not the one asking how to descend from 18,000 feet without navigational guidance.

Someone is feeling mighty defensive
Imp not asking that. I'm just saying it takes some brainpower. We have all seen the different mental math methods to figure out a decent glide path. And with lots of practice you can get pretty good at it. Those of us who fly by hand and figure this stuff out on the fly wouldn't think of VNAV as a very difficult subject.

However, one of my student’s favorite features on his brand spanking new G530 is the VNAV feature. Its tells him what FPM to descend at to get to a certain altitude above a target waypoint. I guess he always screwed this one up royally because he always uses it. He cant figure out when to start his decent without it. He doesn't need to think about VNAV during the landing phase of flight. I'm sure that makes him very comfortable, but he is a fairly seasoned pilot he shouldn't need it right? A monkey could do it right? I see stuff like that and wonder how did the terrorists do it?

What I’m asking is how did those idiots pull of something a lot of my BFR and instrument students can’t pull off? I haven't done much homework but from what I have read these guys weren't that great of pilots and they pulled a real number. Considering the type of aircraft and the speeds involved I think it needs a bit of looking into. Maybe it’s more important than how they figured out where the WTC was?

 

[Yank McCobb]

Basic FMS usage is not rocket science. The 757/756 FMS can be programmed to cross a given waypoint at a certain altitude (and speed, if desired). You can either couple this to the autopilot or hand fly using any of several different different vertical deviation displays.

Again, not really that difficult with even a minimal amount of training if all you are training for is basic heading and altitude control. And VNAV, when you have the type of guidance available on these aircraft, is pretty basic control.

 

[FN FAL]

I'm not the one asking how to descend from 18,000 feet without navigational guidance.

If you have to ask, you probably wouldn't understand anyway.

A couple of times I have ridden up in King Airs to 21,000 feet MSL, took my oxygen mask off, did the hunch back shuffle to the back of the plane, dealt with the exit, freefalled for almost two minutes and still managed to land within walking distance of my tent. No GPS, no FMS, no VOR, no NDB, no charts, no INS.

 

[millhouse21]

Actually, I think the questions about VNAV are not that stupid. There is a lot of scope to screw that up and, in fact, it happened all the time in WW2 with the Kamikazis. A surpising number of them either hit the water before their target or flew over it. Of course, the sept 11 problem was much simplified by the target being (1) Huge (2) having extensive vertical development and (3) not shooting at you. It also helped that they clearly didn't mind overspeeding the airplane.
Having said that, I am actually really surprised that the 2nd guy managed to hit the building. Every time I see that video I keep hoping he will just clip a wing a go spiraling into the water. He can't keep hitting it every time, can he?