FAQ: The V1-VR Terrorist Runway Kill Zone (RKZ) Frequently Asked Questions

What is the V1-VR terrorist runway kill zone (RKZ)?

The RKZ is a zone on an airport takeoff runway between two points called V1 and VR that every large multi-engine jet aircraft, such as Air Force One, must pass through while taking off.

Here is a cockpit video of a 747-400 where the co-pilot can be heard to call out “V1” at 1:24 and then call out “rotate” (VR) at 1:30, as required for all takeoffs.  The runway zone travelled by the aircraft in the 6 seconds between V1 and VR for this takeoff is the RKZ.

If any two engines on a large multi-engine jet can be disabled in the RKZ by a terrorist attack, the aircraft will not be able to gain enough altitude to return to the airport and will almost certainly crash.  The availability of inexpensive, GPS-guided autonomous model aircraft and helicopters (drones and UAVs) that are capable of precisely targeting the runway path of each jet engine in the RKZ makes terrorist attacks increasingly probable.

How big a target for terrorists is the intake turbofan of a Boeing 747 jet engine coming down the runway in the RKZ?

The intake fan diameter of the GE CF6-80C2 turbofan used on Air Force One or a 747-400 is 93 inches (2.36 m) or nearly 8 feet wide (7 ft 9 in).

Are the GPS autopilot systems available for model aircraft and helicopters accurate enough in latitude, longitude and altitude to hit an 8 foot wide target, such as a 747 engine coming down a runway?

The latest drone, UAV, model aircraft and model helicopter GPS autopilot systems are designed to enable autonomous flight and incorporate location accuracy enhancement technologies called DGPS and WAAS.  These GPS enhancements enable a location accuracy radius within the radius of a 747 engine intake ( 1/2 of 2.36 meter diameter = 1.18 meters, or 1/2 of 93 inch diameter = 3 ft 8.5 inches).

DGPS location accuracy according to Wikipedia:

“Differential Global Positioning System (DGPS) is an enhancement to Global Positioning System that provides improved location accuracy, from the 15-meter nominal GPS accuracy to about 10 cm in case of the best implementations.”

WAAS location accuracy according to Wikipedia:

“Actual performance measurements of the system at specific locations have shown it typically provides better than 1.0 metre (3 ft 3 in) laterally and 1.5 metres (4 ft 11 in) vertically throughout most of the contiguous United States and large parts of Canada and Alaska.”

What happens if GPS autopilot systems are jammed or the link to a base station gets dropped during a drone attack in the RKZ?

Inertial navigation systems (INS) can take over from the last confirmed GPS coordinates.  INS compoments are now available for model aircraft autopilot systems either incorporated into the autopilot system or interfaced to the autopilot system.

Are the Secret Service and the Air Force command that operates Air Force One aware of the RKZ?

Yes.  They have been aware of the RKZ since at least 2006 when it was explained to them in detail.

What is V1?

According to Wikipedia “V1 is the critical engine failure recognition speed or takeoff decision speed. It is the decision speed nominated by the pilot which satisfies all safety rules, and above which the takeoff will continue even if an engine fails.  The speed will vary between aircraft types and also due to aircraft weight, runway length, wing flap setting, engine thrust used, runway surface contamination and other factors.”

What is VR?

Per Wikipedia VR is “rotation speed, the speed at which the aircraft’s nose wheel leaves the ground.”  When the aircraft reaches VR, the pilot pulls back on the yoke causing the nose of the aircraft to rotate upwards and causing the wing and flap takeoff configuration to generate lift sufficient to raise the aircraft off the runway.

Why does the RKZ begin way down the runway at V1 and not back at the beginning of the runway?

In the event of a terrorist attack on the engines of an aircraft during take-off, if the attack were to occur while accelerating at any speed  below V1, the pilots should be able to abandon the takeoff safely by “rejecting” the takeoff.

Per Wikipedia:

“A rejected takeoff or RTO (more commonly known outside aviation jargon as an aborted takeoff) is the situation in which it is decided to abort the takeoff of an airplane. There can be many reasons for deciding to perform a rejected takeoff, but they are usually due to suspected or actual technical failures, like an engine failure such as a compressor stall occurring during the takeoff run.

“A rejected takeoff is normally performed only if the aircraft’s speed is below the takeoff decision speed known as V1, which for larger multi-engined airplanes is calculated before each flight. Below the decision speed the airplane should be able to stop safely before the end of the runway. Above the decision speed, the airplane may overshoot the runway if the takeoff is aborted and therefore a rejected takeoff is normally not performed above this speed, unless there is reason to doubt the airplane’s ability to fly. If a serious failure occurs or is suspected above V1 but the airplane’s ability to fly is not in doubt, the takeoff is continued despite the (suspected) failure and the airplane will attempt to land again as soon as possible.”

Here is a video of a Boeing 747-8 performing a test RTO at 200 mph demonstrating the extreme kinetic energy of the aircraft which must be dissipated by the brakes before the end of the runway,  This can only be done safely if the RTO if initiated at or below V1 speed.  This is why the RKZ begins at speeds above V1 when the aircraft cannot be stopped safely with an RTO.

What would likely happen if a Rejected Takeoff (RTO) was initiated in response to a terrorist attack above V1 speed in the RKZ ?

See this story in Flightglobal about a 2009 Kalitta Air crash:  Kalitta revises RTO training after 747’s disastrous post-V1 abort .  It shows what can happen when a bird strike by an 11 oz kestrel takes out one engine in the RKZ and the pilot attempts a post-V1 RTO:

“US freighter operator Kalitta Air has adapted its training procedures to warn crews of the risk of post-V1 rejected take-off, following an inquiry into the overrun which destroyed a Boeing 747-200F in Brussels.

“The aircraft experienced a stall in its inboard right-hand Pratt & Whitney JT9D engine after it ingested a kestrel during the take-off roll on 25 May last year. It failed to stop within the length of runway 20, travelling 300m (980ft) beyond and breaking up into several sections, although none of the five occupants was injured:

“Belgian investigators believe several elements contributed to the crew’s decision to abort the take-off despite the aircraft’s travelling 12kt above V1. After hearing a bang the captain called ‘reject’, seven seconds after the first officer had made the V1 call-out.”

What would likely happen if terrorists were able to destroy two engines in the RKZ after V1, a situation where pilots are drilled in their simulator training to continue to accelerate to VR with the remaining engines and take the aircraft into the air?

See the Yukla 27 tragedyCanada Geese (weighing 5-14 lbs) showed terrorists what can happen if two engines on a large four-engine aircraft are destroyed at VR speed at the end of the RKZ.    The aircraft continues briefly into the air but fails to gain altitude on the remaining two engines and then crashes:

From FlightSafety.org:

“Boeing E-3B Sentry 77-0354 was military Boeing 707-derivative, a.o. equipped and AWACS system. As the plane rotated for lift-off numerous geese were ingested in the no. 1 and 2 engines resulting in a catastrophic no. 2 engine failure and a stalling no. 1 engine. The crew initiated a slow climbing turn to the left and began to dump fuel. The aircraft attained a maximum altitude of 250 feet before it started to descend. The plane impacted  a hilly, wooded area less than a mile from the runway, broke up, exploded and burned.”

Note that no blame was assessed to the Yukla 27 E-3B pilots for this crash.  They calculated their V1 speed for this flight according to regulations.   Above V1 the aircraft could have proceeded to VR and taken off with loss of power if only one engine failed, but there was solution available for what to do if two engines failed.  If terrorists can knock out two engines on a multi-engine heavy aircraft, the pilots of that aircraft will not have a “plan B.”

Why does the RKZ end just at VR and not farther down the runway?

At VR the rotation of the aircraft removes the engines from the linear path they had been following all the way down the runway up until VR.  It is this linear path of the engines which is predictable and can be mapped using GPS and can thus be exploited by terrorists or special forces to ambush an aircraft in the RKZ between V1 and VR.  After the aircraft rotates at VR and becomes airborne its flight path is variable in three dimensions, not just two, so its location is much less  vulnerable to a kinetic attack by a GPS-guided model airplane, model helicopter or other UAV.

What makes the RKZ a “kill zone” for terrorists now?

Model airplanes, model helicopters and other UAVs can now be equipped with increasingly accurate miniaturized autonomous GPS-controlled autopilot systems.  These autopilot systems can be pre-programmed in advance to target individual aircraft engines in the RKZ using known GPS runway centerline coordinates that can be obtained from Google Earth for any airport.

On a targeted runway the GPS coordinates  for a particular aircraft type, such as a Boeing 747, can be predicted with high probability as the aircraft enters the RKZ at V1 and exits at VR.  Then GPS coordinates for each engine as it passes through the RKZ can be calculated by adjusting to the left or right of the GPS runway centerline by the known distance of the engine on the wing from the aircraft centerline and the known elevation of each engine from the runway.

A targeted multi-engine aircraft will almost certainly crash if two engines can be knocked out by terrorists in the RKZ.

Have any terrorists threatened to attack aircraft in the RKZ using model aircraft?

There has been at least one such threat of an attack, but it was an extortion attempt.  See:

German Extortionist Threat to Crash Model Airplane Into Jet Engine

Presentation by Christoph Fischer at Georgetown University, July 22, 1998 (page 17):

“Anonymous remailers allow persons to engage in criminal activity while concealing their identities. President Clinton, for example, has received e-mail death threats that were routed through anonymous remailers. In one case involving remailers, an extortionist threatened to fly a model airplane into the jet engine of an airplane during takeoff at a German airport, the objective being to cause the plane to crash. The threats were sent as e-mail through an anonymous remailer in the United States. The messages were traced to introductory accounts on America Online, but the person had provided bogus names and credit card numbers. He was caught, however, before carrying out his threat.”

This report (uncorroborated so far by blog author, 2branta) provides evidence that at least as far back as 1998, a threat was made to attack “the engine of an airplane” (presumably Air Force One?) “during takeoff.”  It is not clear whether  the extortionist conceptualized the RKZ as presented in this blog, but it appears doubtful that the attack would have been successful if it failed to disable more that one engine in the RKZ as explained in this blog post.

In 1998 miniaturized GPS autopilot systems for model aircraft were not widely available, so the extortionist was most likely planning to use a radio controlled (RC) model aircraft and make the attack using line of sight aiming a single model aircraft at an engine of Air Force One.

If there were multiple conspirators with multiple RC model aircraft, multiple engines could be attacked, which would make destruction of Air Force One as least possible.  However, such an attack would be highly problematic due to the RC model aircraft lacking the precision of GPS runway coordinates and autopilot control, not to mention the state-of-the-art protection afforded Air Force One.

Only by positioning the RC pilot to be standing at the lift-off end of the runway and looking straight down at Air Force One head-on and then flying the RC model at it as it approached could an RC pilot hope to hit an engine  prior to rotation as it thundered closer and closer.  Getting the RC aircraft to impact after V1, but before VR using line-of-sight guessing could be based on careful estimation of when to launch the RC model relative to when Air Force One began rollout.  This would be extremely difficult but possible.

People are still allowed to stand at the end of runways during large commercial jet takeoffs as can be seen at the link.  Notice how the number 2 engine (second from the right) on the approaching 747 almost seems motionless for a time because the person filming is offset a bit to that side.  It is this two-dimensional visual stability of the number 2 engine prior to rotation as seen from the end-of runway vantage point that makes an aircraft vulnerable to both RC model aircraft targeting and GPS autopilot-guided attack in the RKZ.

Could terrorists use off-the-shelf UAV Swarm Technology to coordinate an attack by multiple drones on the engines of large airplanes in the RKZ?

The academic paper at the link (published in 2006) appears to be a do-it-yourself terrorist manual for the planning and execution of an attack on Air Force One, military aircraft, other high value targets to terrorists such as El Al or other large commercial aircraft.  This publicly available research was funded by the US Air Force:

A Distributed Embedded Software Architecture for Multiple Unmanned Aerial Vehicles by Michael J. Matczynski

Submitted to the Department of Electrical Engineering and Computer Science in partial fulfillment of the requirements for the degree of Master of Engineering in Electrical Engineering and Computer Science at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY, May 2006


“In order to deploy intelligent, next-generation applications on Unmanned Aerial Vehicles (UAVs), we must first develop a software architecture that supports onboard computation and flexible communication. This thesis presents an Onboard Planning Module developed from an embedded PC/104 Linux-based computer that communicates directly with the UAV’s autopilot to retrieve telemetry data and update the UAV’s flight path. A serial communication program exchanges data with the UAV’s autopilot while a multithreaded module enables concurrent onboard Mixed-Integer Linear Programming (MILP) optimization. The Mission Manager Graphical User Interface (GUI) monitors the status of each Onboard Planning Module on a team of UAVs using the onboard planning protocol. Two task assignment scenarios are simulated to demonstrate the system operating with both a single and multiple UAV task selection algorithm.”

A terrorist using a single ground station could enter flight way-points for the RKZ into the autopilots of multiple UAV drones.   State-sponsored terrorists could have more development resources to use to perfect UAV swarm technology and to have the UAVs self-assign to attack each engine in the RKZ.  The UAVs could fly in a racetrack pattern designed to fly down the RKZ and then circle back repeatedly to increase the likelihood of being struck by the target aircraft.

Swarm technology could enable a swarm of UAVs to communicate with each other to optimize an attack in a number of ways including surveillance prior to the attack to confirm the identity of the target and the start of takeoff.

A swarm of UAV helicopters could be given autopilot waypoints and be instructed to land in the grass alongside the RKZ, perhaps under cover of darkness,  and await a programmed or subsequent command in hours or days to rise up and proceed to waypoints in the path of each of the engines of a targeted aircraft.

Could Rezwan Ferdaus have used his GPS autopilot controlled model aircraft to attack Air Force One or other large military or commercial aircraft, such as an El Al airliner in the RKZ?

As reported at the link above by Slate’s William Saletan, Ferdaus appears to have acquired multiple GPS autopilot-controlled model aircraft capable of flying to runway waypoints obtained from Google Earth within the probable RKZ of a “high value target” of his choice:

“Everything I’m going to tell you about Ferdaus comes from the affidavit, which cites his own recorded words. He majored in physics at Northeastern University. He hated the United States. He loved electronics. He learned robotics. He took apart cell phones and turned them into bomb detonators. One day he got a bigger idea: He would hit high-value U.S. targets from the air. He would use remote-controlled aircraft.

“The planes would carry explosives. Ferdaus chose the Pentagon as his first target and the Capitol as his second. Using library and café computers to avoid being identified, he looked up Web sites that sold large remote-controlled model planes. He learned that they could carry 40 to 50 pounds of payload. These weren’t drones, but they were affordable—less than $3,000 per plane—and Ferdaus figured out how he could use them. He found a model that was nearly six feet long and four feet wide. It could be programmed to fly on autopilot, at a speed of up to 160 miles per hour, to a target defined by GPS coordinates.

“The logistics were easy. Ferdaus used a fake name to get price quotes. He arranged the transactions through an alias PayPal account. He scouted a location—East Potomac Park—from which to launch the planes. He determined that he could get the coordinates from Google Earth. He bought spark plugs, batteries, and ammonia from various stores. He bought rocket motors from Toy ‘R’ Us.”

Ferdaus chose not to make use of (or was not aware of) the lethal kinetic force that could be generated by an object as small as a 5-10 lb, such as a Canada Goose, if it were to impact a target at 150 knots.  The model F-4 Phantom and F-86 Sabre jets in the pictures claimed by the FBI to  depict the models that Ferdaus planned to use are powered by mini-jet turbine engines approximately a 5 in. diameter and 5 lbs. in weight which would act like a cannonball if they impacted an airliner jet engine in the RKZ.

No onboard explosive payload would need to be engineered into his model airplanes if the kinetic force capability could be guided directly onto a vulnerable target, such as a person or into the intake of a jet engine in the RKZ.  This was a “failure of imagination” by Ferdaus.

How can the Runway Kill Zone (RKZ) be protected from terrorist attacks?

The RKZ requires electronic and human surveillance at the physical RKZ location on the runway and in the vicinity of the runway and airport to provide detection and warning of UAV drone launches and intrusions.

Aerial surveillance of the RKZ and vicinity using defensive military-grade drones should be instituted at high profile airports, especially for Air Force One and VIP takeoffs.  Surveillance drones might be equiped with infrared sensors and countermeasures to defeat attacking UAV drones, for example using jamming or lasers.

Government surveillance drones and other drone detection systems are needed now to counteract terrorist surveillance drones which may penetrate airport airspace to locate and track targets to help time attacks precisely in the RKZ and elsewhere.  Non-state opponents of governments are already using drones to defeat government attempts to conceal and secure government activities and events on the ground.  See this Village Voice story on an inexpensive helicopter drone acquired by supporters to Occupy Wall Street.

RKZ surveillance drone operators and sensors at airports should be in live radio contact with pilots during takeoffs to permit last-second warnings for pilots to abort takeoffs prior to reaching V1, if an attack is detected.

The current limited NOTAMS program notifying the public and local Academy of Model Aeronautics (AMA) affiliated radio controled (RC) airfields and members not to fly during VIP (presidential) visits should be expanded to a broader program of public awareness to be alert to suspicious persons and activity involving all model aircraft capable of autonomous GPS autopilot flight.  The FBI press release on the arrest of Rezwan Ferdaus is a step in the right direction of alerting the public to model airplane danger.  But the press release does not mention the danger from kinetic impact on a jet engine in the RKZ posed by the equipment that Ferdaus possessed.  Here is an example of the Christmas 2011 NOTAM:

“Posted 12/14/11

“A new FDC NOTAM/TFR has been issued for the upcoming Holiday Season for the island of Oahu and the area surrounding Honolulu, HI beginning Saturday, 12/17 at 10:00p until 11:59p HST on Monday, 1/2/2012. The TFR is issued for security purposes to cover VIP movement in this area. Outdoor model aircraft operations are prohibited within the 30nm circle for the specific times listed below. Please note that TFRs are subject to change with very short notice. Check back often for the most current NOTAM/TFR information. Timely alerts are also available on the web or on your cell phone at: Twitter.com/amagov.”

Citizen vigilance, such as that promoted by the AMA below, must be greatly expanded to involve people near civilian and military airports who can spot and report suspicious activity:

AMA and aeromodelers everywhere outraged at terrorist’s plan to attack Pentagon, Capitol with RC model converted into a UAV

“M U N C I E – The Academy of Model Aeronautics is shocked and outraged by the actions of a 26-year-old Massachusetts man arrested this week on federal charges for his intent to use an RC model airplane reconfigured as a UAV, similar to a military drone, for an explosive-laden attack on the U.S. Capitol and Pentagon. The suspect is not an AMA member nor has he been confirmed as being a model aviation enthusiast.
“’When an otherwise safe and wholesome hobby becomes the focal point in a planned terrorist attack, we are as outraged as all citizens,” said AMA Interim President Mark Smith. “Like all Americans, we appreciate the professionalism of the FBI in this case. The AMA’s 143,000 aeromodelers throughout the country pledge to keep a vigilant eye in their communities on any suspicious activity involving RC aircraft.’”

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