The end of 'Terrorist Couldn't Fly Planes That Well' threads

reply to post by Boone 870


Looks like weedwhacker has the better version of the story. The terrorist just entered manual settings to the autopilot. Like you said, they could just pick out legs of a path for their flight plan.

Originally posted by dbates

Lastly, civilian GPS signals are accurate to about 50 feet and that doesn't mean that it's guranteed to be 50 feet off. It could be dead on, 50 feet off, or anywhere in between. That's why I initially said that the second plane banked towards the end. GPS navigation isn't perfect, but more than accurate enough to point the plane right at the building automatically leaving the pilot to make only a minor adjustment.

Thanks for the post dbates. Let me respectfully suggest you do not know what you are talking about. GPS signals can be very accurate, standing still such as in surveying, where you wait several minutes for a reading. This is not true in an airplane and especially in an airplane travelling at 500 mph. I would respectfully suggest you either retract your 50 ft. accuracy statement or state the conditions under which that accuracy can be maintained.

Let me respectfully remind you that the airplane was traveling 733 feet per second. So to have an accuracy of 50 ft. the update rate would have to be 1/14 of a second plus the time to the display, the computer and the autopilot. That, of course is assuming that he autopilot could react instantaneously which it can't. An autopilot takes an input and transmits the signal to sevos which then actuate the proper flight controls. This all takes time and is not done for 50 ft. accuracy. Maybe 3000 feet but not 50 ft.

So 50 ft. accuracy could not be maintained in a Boeing 767 under the conditions they were allegedly flown in the World Trade Center or any conditions whatsoever unless it was parked on the ramp.

Thanks for your understanding.

Originally posted by johnlear
GPS signals can be very accurate, standing still such as in surveying, where you wait several minutes for a reading.

Wait! It appears that we're both wrong. According to this Flight Deck article GPS accuracy up to one metre has been available to aircraft for years.

Differential GPS -- corrected GPS signals accurate to within one to three metres -- has always been available to the public.

The corrected GPS signals are already used in aviation, where it really matters

Your implication that GPS only works while standing still is not true. In relation to the signal speed from the satellite, aircraft are stationary objects. What is the speed of an electronic signal? What is the speed of the aircraft?

Need more proof.

Early 1980's science produced 1 cm per 10 km of baseline (one part per million). This are now a turnkey commercial products from many vendors

Almost all levels quoted here are for dynamic users, including aircraft.

• Standard DGPS............. 4 m
  
• Second Generation....... 75 cm
  
• PPS DGPS.................... 35 cm
  
• Narrow Correlators...... 10 cm
  
• Kinematic (Phase)........ 4 cm
  

www.oc.nps.navy.mil...

The accuracy of GPS in-flight is more than enough to let an airplane fly itself into a building. My guess is that on average it's no more than a few feet off. Some of that probably has to do with unexpected wind gusts. Pilots in commercial aircraft have been reduced to push button operators used for take off and landing. Things have changed since you started flying back in the 1960s. Welcome to the 21st Century John.


[edit on 28-11-2007 by dbates]

Originally posted by dracodie
... and i doubt the goverment would keep the use of the automatic flight planning system software by the terrorists omited since that would only back up the official story of how they skillfully piloted the planes

Unless that would lead to more questions on their training and uncovering stuff the perpatraitors don't want us to know.

Originally posted by dbates

The accuracy of GPS in-flight is more than enough to let an airplane fly itself into a building. My guess is that on average it's no more than a few feet off. Some of that probably has to do with unexpected wind gusts. Pilots in commercial aircraft have been reduced to push button operators used for take off and landing. Things have changed since you started flying back in the 1960s. Welcome to the 21st Century John.
Thanks for the post dbates. And thank you for the welcome into the 21st century.

Thanks for the post debates.

Differential GPS, while more accurate is used only for approaches because it requires an alternate signal which it compares to the signals received from the GPS satellites. The alternate signal is stationary and is on the ground.

This type of accuracy is not possible during normal GPS operations because it is:

1. not feasible to have the alternate source everywhere and,
2, there is no reason for that kind of accuracy unless its on approach.

Abstract: The Department of Defense (DOD) and the commercial airline industry are in the process of replacing the instrument landing system (ILS) for aircraft precision approach landings. The use of differential Global Positioning System (DGPS) is thought to be a viable replacement for ILS precision approaches. This thesis explores the integration of an INS, DGPS, Barometric Altimeter, Pseudolite, and Radar Altimeter for a tanker type and a single engine aircraft precision approach. These devices are integrated using an extended Kalman filter (EKF). For the tanker type aircraft federal Aviation Administration (FAA) requirements for a Category I and a Category II precision approach were met when an INS, DGPS, Barometric Altimeter, and Radar Altimeter were integrated. Category III precision approach requirements were met for the single engine type aircraft when the same sensors were integrated

.


www.stormingmedia.us...

The accuracy of GPS in-flight is more than enough to let an airplane fly itself into a building. My guess is that on average it's no more than a few feet off. Some of that probably has to do with unexpected wind gusts. Pilots in commercial aircraft have been reduced to push button operators used for take off and landing.

Again, dbates, this is referring to differential GPS which is an entirely different system than plain vanilla GPS which is all that would have been available to those alleged hijacker pilots.

But thanks for your posts. Although it has been 7 years since I stopped teaching aeronautical navigation as an FAA certificated MNPS check airman I always enjoy a discussion on navigation and navigation systems.

I was also one of the last check airman/navigators to have received the FAA Navigators certificate. That check ride requires overwater navigation by celestial shots and computation only.

I got in just under the wire in 1977 because the Boeing 707's I flew for Trans Mediterranean Airways in Lebanon
still had the hole in the top of the cockpit for the Kollsman MIL-S-5807 periscopic sextant.

Things have changed since you started flying back in the 1960s. Welcome to the 21st Century John.

Yes, debates they have changed a lot. Thank god Omega is gone forever. One thing hasn't changed though and that is the accuracy of the GPS that was available to the alleged hijackers was no better than half a mile.

Thanks debate, your input is greatly appreciated.

Slight correction, the pilots would have to either, delete all waypoints in RTE 1 and add WTC coords to the end and press EXE, or add WTC coords to RTE 2 then activate then EXEC. Bit more complicated than you guys said.

Anyway, the 767 uses a fairly inaccurate Inertial Navigation System corrected occasionally by the GPS. I have doubts that the INS would be accurate enough to fly it directly into WTC, and I for one, and many real pilots, certaintly would NOT trust it doing this accurately, especially twice. Go ask at PPRUNE.

About autopilot, It's generally NOT a good idea to override the autopilot, it will either disconnect, or when you let go, it will go back to its original course rather quickly. If you had the autopilot engaged, then you'll be battling its innaccuracies WHILE trying to hit an object slightly wider than a runway at 500mph. ARGHHHHH.

There is definately no way autopilot was used for hitting the world trade centres. Maybe for inital lineup, I think I've suggested that before here... but it is both easier and more precise hand flying into a rather small object.

And look at the flght paths of the aircraft, if they were on autopilot then the approach would most likely, of been straight in without any turns. Was that what we saw? No. And there's no way that autopilot would have been abled to bank that hard so close to the target while still being abled to hit an object 200 feet wide.
upload.wikimedia.org...
images.indymedia.org...
Autopilot isn't even designed for that, if a plane where that close to a waypoint it would just level off and fly straight and level in the general area of the waypoint. If they had the autopilot engaged and were overriding it, then they'd litterally be battling wth it.

Disengage autopilot, and hand fly.

Put it this way, do you think high speed passes at airshows are done on autopilot? Also, ask a real pilot if they could hit a 200 foot wide object at 500mph using INS. He'll say no.

Let's ask John, a pilot of over 19 000 hours.

John, if you beleived WTC was real, do you think you could get autopilot to bank steeply, very close to WTC, to hit it dead on right in the centre? Do you think you could battle the autopilot to hit a target slightly bigger than a runway?

You should also try proffesional pilot forums (e.g. Airline Pilot Central, PPRUNE).

Pilots in commercial aircraft have been reduced to push button operators used for take off and landing. Things have changed since you started flying back in the 1960s. Welcome to the 21st Century John.

Please learn what you're talking about.

99.9% of landings are HAND FLOWN, ALL takeoffs are HAND FLOWN, MOST approaches are HAND FLOWN, most departures are HAND FLOWN. Autoland systems have been availible since the early 60's with the VC-10 and LNAV and VNAV have been availible since the 70's.

Since the 70's, I dare say the automation in flying has not greatly increased (Gulfstream 550 is diferant). FMS, VNAV, LNAV, autoland, autothrottle, autobrakes... and so on have always been around back then. Modern aircraft have much better presentation of this, but navigation is pretty much the same.

Really insulting. No real wonder why pilots have horrible pay yet astounding training costs... they're 'push button operatiors'.

Fly-around routes on missed landings (for whatever reason) are already in the system and the FMS will do everything for you if you let it.

Only if you program it.

In an attempt to maximize fuel effeciency the FMS can adjust the plane's altitude as it calculates the weight changes during in-flight fuel useage.

The FMS will display OPT and MAX altitude availible for your given weight, however, provided you have VNAV engaged, you will have to tell it what altitude to cruise at by changing 'CRZ ALT', in the PERF page of the CDU and entering it into the MCP.

[edit on 29/11/07 by JimmyCarterIsSmarter]

I've experienced exactly what John is talking about myself. When a GPS is receiving signal from ONLY the orbital transmitter satellites, it will have a lower accuracy resolution. In my experience, between 85-110 meters in a slow moving aircraft. On approach, the differential signal transmission is picked up and the resolution almost instantly jumps to less than 5 meters. In fact, the GPS will sometimes pick up the ground based differential transmitter for a few miles and that resolution is achieved.

I don't know for a fact or have any real training on the ins and outs of real GPS navigation, but for once...something John Lear says actually jives with my own experience!

Hey John, got anymore of those tinfoil hats? I might need one!



[edit on 28-11-2007 by StudioGuy]

[edit on 28-11-2007 by StudioGuy]

I hate to break it to you John but you are out to lunch on the accuracy of GPS units. Even the fuzz built into civvie units would allow you to pilot things at very high speeds - it is all about the polling rate at speed.

Besides, we are talking about a black op system with zero fuzz - and anyone else can have that too, heck I can grab one at work that the forestry surveyors use.

reply to post by dbates


That's insane. Look at the actual flight paths. Look at the time in-flight. You mean to tell me that these people who trained and prepared for this mission took THAT long to plot their flight plan. For the love of God, they only needed to enter ONE waypoint! They didn't even need to enter in a complete flight plan. Your position is meritless I'm afraid. It takes less than a minute (if that) to enter a waypoint and activate. My kid can enter an entire flightplan into my Garmin 530 while I'm taxiing and that is no more/less complicated than the FMS systems.

reply to post by Icarus Rising


Yes and the Pilots for Truth have long ago debunked this theory as a hijacker would NEVER have the key access codes for the GPS program. Ground/tower control immediately receives the coordinates changes etcetera so they would be aware of either a collision or impact point.

This is an argument which has long since been debunked.

Try again.

pilotsfor911truth.org...

Originally posted by Boone 870
reply to post by weedwhacker

 

Just a little correction for you weedwhacker. Mohamed Atta was from Egypt. He flew American 11 into the North Tower. Marwan al-shehhi was from the UAE. He flew United 175 into the South Tower.

Both pilots had their commercial ratings. Both pilots had their instrument ratings.

Thanks, Boone...I was unaware of their specific nationalities and their ratings. SO, they weren't quite as inexperienced as initially claimed by some ATS posters? They knew how to tune the VORs, proablly knew how to switch the EHSI between the 'MAP' depiction mode and the regular 'HSI' mode that they'd be familiar with...for the non-pilots, if you tune a VOR and are within range (about 200 miles, at a cruise altitude above 30,000) you can steer to the facility. A descent from 30,000 would normally begin about 100 miles out - they would have to throttle back to control airspeed...in fact, from 100 miles at 30,000 we simple pull back to idle thrust...this in the real world. Don't know what they did.

reply to post by dk3000


dk3000....huh?

Have you been reading any of the previous posts? No one needs "GPS codes". "Tower/ground control" statement shows you don't understand the ATC system.

Capt Lear's B707 story with the Sextant hole in the cockpit ceiling reminded me of how far technology has come in aviation navigation.

Long-range overseas navigation relied on dead-reckoning, starsights (at night?) for decades until the INS (inertial nav system) was invented. Three gyros, one in each axis, with sophisticaed instrumentation to measure the precession of each gyro as it was moved, and to use that data to calculate velocity and heading relative to a starting point (the point of iniatilization). They were so accurate, they could tell when you initialized in the wrong latitude since they could detect the Earth's rotation. (Of course, couldn't tell the diff from N and S latitude, but that's another story...)

Anyway, mechanical INS were improved with (laser ring) gyros with no moving parts (unless you consider light a moving part). Then, as in the early B757 and B767, the laser ring units were fed updates from VOR and TACAN (the DME portion) data for a more accurate self-updating system. Lastly, GPS is now used, not in all jets, depends on the airline and whether they've retrofitted their fleet. AND, finally, as Capt Lear mentioned, the MNPS requireaments are built in depending on location and altitude...certain various airspce requirements have varying MNPS restrictions...MNPS might be 4.0 NM whilst on the North Atlantic tracks, but 0.3 NM when in the terminal area of an aerodrome. Precision approaches using GPS (enhanced) are becoming more and more prevalent...

Hello again, dbates

I think you mentioned your Flight Safety sim experience in a Gulfstream.

Without too much hyborbole, that is probably considered to be a favorite of any Corporate pilot out there! State 0f the Art, no doubt...and the funny thing is, corporate aviation (FAR Part 135) seems to be more cutting-edge (bleeding-edge?) tech and avionics well before Part 121 carriers can get thru the morass that is the certification process. (read: FAA bureaucracy).

You mentioned a 'woman's' voice saying 'pull up' and 'altitude'. The GPWS in Part 121 airliners has been in place for decades, and is a certification requirement, as well as on the 'MEL' (minimum equipment list) as a requirement for dispatch. The GPWS, when incorporated into the GPS data, is referred to the 'EGPWS' since it is 'enhanced' with terrain (but not buildings/sturctures) data.

Perhaps a Corporate Gulfstream uses a woman's voice for their GPWS. McDonnell/Douglas used a woman's voice in their MD-80 PAWS system...but the industry standard still has the 'Whoop Whoop Pull Up!' among other audible warnings, in airliners.

The GPWS is getting ever-more sophisticated, with 'soft' warnings and 'hard' warnings...it is programmed to respond depending on the phase of the flight...

But, I strayed off-topic. The perpetrators on 9/11 didn't need to know all of this, I just included it for everyone's edification.

come on dude, they couldn't even land properly!

Flying a plane is much like learning to play a musical instrument.

A newbie pilot wouldn't be able to pull off the pentagon and WTC approaches! You would need an expert, someone with much experience with that sort of plane.

So if flying a plane is much like playing a musical instrument and this were a hypothetical guitarist jam, your basically expecting a 4 newbie suicidal guitarists who could barely play a chord let alone a guitar solo, to play as convincingly as Jimi Hendrix or Steve Vai without anyone being able to tell the difference. Not possible, doesn't happen.

Originally posted by Insolubrious
come on dude, they couldn't even land properly!

Flying a plane is much like learning to play a musical instrument.

A newbie pilot wouldn't be able to pull off the pentagon and WTC approaches! You would need an expert, someone with much experience with that sort of plane.

Since when is a certified multiengine commercial pilot considered a "newbie"?

Hitting a building would be a lot easier than pulling off an exacting runway approach, which is one of the requirements for the above licenses.

Originally posted by Insolubrious
Flying a plane is much like learning to play a musical instrument.

And the FMS is the equivelent of having a player piano. Watch as this untalented individual plays Beethoven's Fifth, Symphony. Look ma, no hands.

Originally posted by nicepants

Since when is a certified multiengine commercial pilot considered a "newbie"?

Hitting a building would be a lot easier than pulling off an exacting runway approach, which is one of the requirements for the above licenses.

I can't believe you got three stars for that comment!

Yeah - NEWBIES. Did these guys run a few hundred commerical routes before hitting the trade towers? I doubt it! There is a difference between a certified multiengine commercial pilot who has just got their license and a certified multiengine commercial pilot who has been flying commerical aircraft for over a decade.

I can land a Boeing in ms flight simulator no probs, but trying to hit the WTC is a whole different ball game. Consider also they had to hit the correct tower and were probably aiming for the south and north faces like they did. I am not sure but the WTC isn't much wider than a runway designed to land large commerical jets. So really they do have to be pretty accurate!

[edit on 29-11-2007 by Insolubrious]

reply to post by Insolubrious


Insolubrious, with all respect,

You are trying to equate your experience on a desktop computer and a Flight Simulator program on such with either a real, multi-million dollar (about $20 million for a full system, not including the computers and the hydraulics needed to run a Full Flight Simulator)...

Your desktop will never be ANYWHERE close to a full motion sim designed to train airline pilots. Sorry, as an amateur you can understand some of it, but in a real sim we use airline-appropriate checklists, we re-create as closely as possible the real world. That is the training environment.

Doesn't exlain the fact that witnesses at the scene described the plane that hit one of the towers as having no windows and something attached to the bottom of it...not to mention the amount of heat that burned the metal in those towers...or the fact that a PA paper said that plane that crashed had been docked shortly after take off and the clean up crew said it looked almost as if metal was just thrown down- there were no recognizable plane parts. One theory about planes being flown by terrorists cannot outweigh the other abnormal facts and anomalies.

Originally posted by Insolubrious

Originally posted by nicepants

Since when is a certified multiengine commercial pilot considered a "newbie"?

Hitting a building would be a lot easier than pulling off an exacting runway approach, which is one of the requirements for the above licenses.

I can't believe you got three stars for that comment!

Yeah - NEWBIES. Did these guys run a few hundred commerical routes before hitting the trade towers? I doubt it! There is a difference between a certified multiengine commercial pilot who has just got their license and a certified multiengine commercial pilot who has been flying commerical aircraft for over a decade.

I can land a Boeing in ms flight simulator no probs, but trying to hit the WTC is a whole different ball game. Consider also they had to hit the correct tower and were probably aiming for the south and north faces like they did. I am not sure but the WTC isn't much wider than a runway designed to land large commerical jets. So really they do have to be pretty accurate!

[edit on 29-11-2007 by Insolubrious]

Is it your contention that ramming an airplane into a building would be just as difficult as lining one up on final approach? And I'm talking about real-world flying, not a flight sim.

To be licensed, a pilot must perform a takeoff, flight, emergency procedures, and landing without any assistance by an autopilot or by an examiner. It requires SEVERAL HUNDRED HOURS in order to get the licenses mentioned above. That's hardly a "newbie". If you can line up a plane for a safe landing on a runway, you already posess the necessary skills to crash an airplane into a large building.