The NON-LETHAL anti-Hijack ArmorY

Versus RoboLander

(see Story Below the Table)

One advantage of non-lethal weaponry in civil disorder crowd-control situations is that the truly dangerous become obvious and easily discriminated from innocent civilians. The true threats may be confrontational from the outset, carrying or wearing gas masks and goggles, and may be wearing body armor as protection against rubber or metal bullets.  However, a “sleeper” assailant in an aircraft hijack attempt will have the significant advantage of total surprise, covert backup and knowledge of the aircraft’s NL weaponry. The vulnerability of passengers in a confined space is a major consideration for any use of non-lethal weaponry. Many of the measures below could well be lethal to the aged, infirm, asthmatic and very young. In the case of premature or mistaken activation, would this be acceptable?  

By comparison there should be no unacceptable outcomes in the case of a reversion to ground flight-control (the concept that's become known as RoboLander).

The table below is a disparaging refutation to the proposition that any “non-Lethal Weaponry” can ever protect an airline crew and passengers or restore confidence to the air-travelling public. The final table compares the RoboLander concept’s strongpoints as a comparison benchmark.

Any comment (pro or con) is welcomed   (



(Application / Advantages)


Use in Aircraft


Stun grenades

(Shock and distraction)

Short-term effect only

Not recommended (large over-pressures) and induces passenger and cabin crew panic


Dazzlers and/or strobes

(Temporary blinding)

Can cause permanent eye damage for other pax – vitreous floaters

Nil advantages for crew. defeated by sun-glasses or goggles.



(Good against vehicles, in ambush situations or where fortifications seek to keep personnel out - barbed wire)

Roof deployed net would be inhibited by seating and would not affect adversary’s ability to manoeuvre.

Nil advantages (except in the form of manacles or shackles after overpowering assailant)


Slippery agents -gel, foam, oil

(Destroys adversaries mobility and manoeuvrability – but also impairs all present)

Good where adversary requires mobility (mob attacking vehicles)

No advantages (too many grip surfaces – such as seating – for it to usefully impede mobility)


Intoxicants spray

(Produces inebriation / loss of concentration)

Crowd control – good quiescent effect over time.

No tactical advantages. In an aircraft it produces undesirable characteristics in some individuals (emphasised by increased cabin altitude)


Mustards (aerosol spray or foam application) and irritants

(As distinct from mustard gas and CS gas)

Similar effect to pepper spray but tends to affect both skin (blistering) and eyes. Very aggressive but tends to only work well for control of highly fluid riot situations.

Inappropriate for in-aircraft use ( aerosol would spread quickly via air-con system and distress many individuals)


Blinding Agents/ obscurants/

Smoke generation

(Pupil Dilater Can be applied by aerosol spray (or thrown “drink”). Could also be covertly introduced (slowly) into cabin via cylinder injection into aircon air. Atropa Belladonna (deadly nightshade) is also readily available and could be used to blind pilots or cabin-crew.

Mydriatic and cycloplegics are the class of drugs typically used in pupil dilation?. Chemical names of the cycloplegic drops are atropine, cyclopentolate, homatropine, and scopolamine. How long does dilation take? Mydriatic are fast acting compounds and  full dilation of the pupil occurs in 20 to 45 mins.How long does dilation last? 2 to 6 hours. Typically individuals experience blurring of near vision and increased sensitivity to light. Distance vision less affected by dilation than near vision.

Combined with irritant initially would be effective in subduing individual who assumes permanently blindness. Effective against terrorist or air-rager. Smoke would tend to induce panic amongst passengers – be wary of a rush to one end of the aircraft, causing CofG change control problems (but smoke/misting would not stop fall-back triggering of pencil-fused plastique bomb in a money-belt) or breaking of a frangible pen type toxic gas cylinder/vial. Also will not deter a confederate if it was applied discriminately to an individual. Offender will be alert to this defence possibility.


Acoustics and sirens

(Directed acoustics against crowds can cause extreme discomfort)

Effectively countered by unseen ear-plugs and/or rapidly donned ear-muffs. Probability of passenger permanent hearing loss.

Not recommended within fuselage (due panic-inducing resonant effect). Will confuse momentarily then enrage,- but not disable.


Calmative -soporifics and sleep agents

(Aerosol spray can be surreptitiously applied via airconditioning system –by injection from cylinder)

Slow acting (but suitable for resolving developing air-rage situations) ). Too slow to work in comparison with nerve agents. Could be an adjunct to the plumbing required for the proposed AWIGG fine-mist water-spray fire-extinguishant system

Good for passive resolution of in-aircraft situations (however requirement is for pilots to take early precautions (full-face oxygen-masks)


Nerve agents –disabling

(Single shot disguised syringe (can be “palmed” and suddenly injected hypodermic fashion))

KGB weapon (best known in lethal dosage use by Bulgarian Secret Service in umbrella tips) – toxicokinetics can immobilize an adversary for hours. Aggressive therapy depending upon the dosage

BZ (psychochemical incapacitant) would be appropriate. Inappropriate for general cabin use via spray system (poss lethal effect upon some pax/asthmatics). Inject will not work where offender has a covert confederate observing.


TASERS (stun guns) /directed energy

(Effective close-in disabler -quickly incapacitates an adversary)

Probable destructive or disabling effect on systems of any misfire (AD) or miss that connected with aircraft (bonded metal skin carries electrical earth return).

Not recommended in FBW a/c. Can also fall into the wrong hands.


Explosive decompression

(works best at altitude but ineffective in early climb/descent)

Best rendered by explosive bolts blowing out a panel (outflow valve opening is too slow to be “explosive”). Shock efffect is shortly thereafter followed by acute hypoxia within two minutes above 18,000ft AMSL

(possibly lethal to the infirm)

At altitude the effect is shock/distraction & surprise and  may enable offenders to be tackled/manacled. Does not work at lower altitudes because of lesser pressure differentials. SkyMarshal would need portable oxy/experience of phenomena


Non-explosive decompression

Works only at cruise altitude. (Allowing the insidious onset of hypoxia)

Distraction of collapsing pax may confuse hijackers / may then induce desperate action.


Malodorants, blinding lasers, thermobaric (prolonged overpressure controlled blast), freezer-spray (dry-ice)

blinding lasers need to be directed and will cause pax retinal damage. Thermobaric is debatably not NL. Freezer-Spray compressed CO2 needs volume to be effective

Impractical – yet would all be great passenger deterrents. Hypothermia Shock effect could induce heartattacks.


Incapacitant gas plus stun-grenades and laser-light strobes.

[Multi-sensory (sudden sensory overload causing

distraction & incapacitation)]

Paralysis not guaranteed at dosages that would be non-lethally safe to all passengers (some deaths may have to be accepted amongst the young, elderly, infirm and asthmatics from shock and inhalatory side effects). System stressful for crew  decision to use so cabin crew would tend to downplay any situation for fear that it might be used prematurely or mistakenly. Anaesthetics always applied dosimetrically (age and body-weight). Because of  distribution, some individuals would get unintended rapid high dosages and others would get insufficient.

Would stop all terrorist activity that excluded fused explosives – but would be a great deterrent to passengers if they knew of its presence. Any claim “that effects could be tailored” should be suspect until proven.

Not as socially acceptable as #Q below.

No safeguard against the sleeper first officer (but RoboLander would be)


“Non-lethal” shootdown

[In a “weapons of mass destruction” sense only]

Pilots are quietly vowing not to squawk the hijack code because of fears this policy may be misapplied/accidentally applied.

e.g One of the Anchorage diverted aircraft (KAL 747) on 11 Sep mistakenly squawked the hijack code due to a misunderstanding. Under this policy “poor English” may well be shot down.

FOR COMPARISON (see Article on NLW's below)

Q. Fail-safe reversion to ground control. 

(the RoboLander Solution)

Great deterrent effect (particularly once demonstrated to be an effective system)

Works both passively and actively and always alerts outside agencies to what’s occurring onboard.

Insufficient space here to point out all the comparative benefits



Quest: So why cannot hijackers just take the fire-axe and destroy wiring bundles and CB's etc and cause the aircraft to crash anyway?

Answer: In the future, once wiring bundles are remoted and inaccessible and circuit-breakers are physically inside the code-locked E&E bay, (replaced in the cockpit by status lights) then hijackers should be unable to "down" the aircraft. However the RoboLander system is presently designed only to stop normal hijackings and suicide terrorists’ targetting routine. Unless systems were physically isolated, hijackers operating with impunity could always "down" an aircraft. This may not  be the case in future designs .

Quest: It could not be solely controlled with today's non-FBW airplanes since the pilot can fly it anywhere he wants manually - and that is the way it almost has to be. 

Answer: Consider the dual-tandem operation of virtually all Electro-Hydraulic Valve (EHV) control surface actuators used by autopilots (and a similar parallel redundancy for "cable grabber" autopilots that use electric motors).  Autopilot EHV's always receive their hydraulic power from a DIFFERENT hydraulic source than the pilot's controls’ mechanically-operated hydraulic valve.  This is per-design so that a cable failure to the surface will still allow the A/P to fly the airplane in this failure condition (a parallel control path).  This feature could be exploited in such a way to rob control from hijackers in the cockpit.  The system that reconfigured the aircraft to make the cockpit "go dark" could close shutoff valves to the mechanical input valves to the control surfaces, thereby leaving only the autopilot EHVs with hydraulic power.  It becomes even easier when the airplane is full fly-by-wire (a la Airbus family and 777) since you can simply ignore the pilot's wheel (or side-stick) electronic inputs to the flight control system.  . See

1.  RoboLander concept also applies to some other potentially lethal non-hijack emergency scenarios.

2. Gives passengers best fall-back chance for survival in comparison with all other methods.

3.  If pilots are killed or incapacitated, even an F/A or SkyMarshal can activate it. [That activator button will always remain HOT under its guard].

4.  If all onboard are incapacitated by nerve gas the aircraft should still recover - notwithstanding all else – via the passivator mode.

5.  Removes passenger fears about potential shoot-down threat (presently a huge deterrent and a case for pilots not to declare an emergency).

6.  If situation is brought under control then autonomous control can be returned to pilots by the ground (via pilot's pin no).

7.  If “latching” is lost with the ground via the satellite data-link, then control auto-reverts to the pilots via an onboard latching safety-interlock.

8.  SkyMarshal can remain incognito and await further intervention opportunity.

9.  Fears about pilot being forced to divulge pin-code within the (max) 20 minute passivity period can be overcome by pilot chomping on an anaesthetic false tooth (or mouthguard) - pilots could even short-term “gas the cockpit”.

10.  Fuel dump can be initiated by the ground control (as a further RoboLander limiter function).

11.  The requirements of the concept are not dissimilar to the infrastructure being set up by the use of ADS-B and Safe Flight 21 Technologies. Auto-flight capabilities are very mature.

12. VDL Mode 4 data-link might be adaptable to the concept of bringing a hijacked airplane to a safe landing under ground control. See Safe Flight Link Evaluation Team Report at

 13.  RoboLander is irreversible but not  irrevocable  and is a safety-latched and  fail-operable design that is presently in Proof of Concept study with a major aerospace manufacturer.

From Air Safety Week (12 October 01)

Non-Lethal Weapons Suggested to Incapacitate Terrorists in Airliners

            The U.S. military is suggesting the use of non-lethal weapons as a means of combating terrorist attacks in the air by disabling the assailants…. not killing them outright, but depending upon the tactic, either distracting, immobilising, de-motivating or inducing paralysis.

            The concept, articulated to airline industry officials in a briefing prepared by the U.S. Department of Defense Joint Non-Lethal Weapons Program, may represent a hypothetical “bridge too far.” It envisions the use of multiple devices in a simultaneous assault on the senses that would disable everyone in the cabin, to include cabin attendants and any sky marshals that might be aboard. In the face of blinding lights and piercing shrills from sirens, any would-be hijackers might not be the only ones curled on the floor in the fetal position, their eyes squeezed shut and hands clasped over their ears.

            However, a less aggressive use of non-lethal devices in the immediate area just outside the cockpit, in what might be called a “security zone” extending a few feet back from the cockpit door, may be worth considering.

            “We offer some technologies that the airlines could leverage,” said Colonel George Fenton, a Marine Corps officer at the joint non-lethal weapons program office at the Marines’ base in Quantico, Virginia. With non-lethal weapons, he suggested, “It becomes too hard to take over an aircraft. Pilots would not have to carry guns.”

Not lethal, but not harmless

            One point needs to be stressed at the outset. Non-lethal weapons are not harmless. The operative term “to incapacitate…while minimizing fatalities” (emphasis added) is significant (see p. 1 box). As Fenton cautioned, “There is no guarantee” that fatalities will not result when non-lethal weapons are used. However, unlike handguns, non-lethal weapons are not designed to kill. Rather, they are intended to change an assailant’s behavior – from one of an offensive mindset to a defensive, self-protective mentality. In terms of the classic “fight or flight” syndrome, non-lethal weapons are intended to induce a strong desire for “flight.” This can take the form of so incapacitating an assailant that he flees, or is reduced to curling into a defensive ball on the floor.

            As Col. Fenton explained, non-lethal weapons are designed to deny use of the body’s five basic senses, of the ability to think (cognition), and the ability to move (motor skills). These are the seven areas, if you will, against which non-lethal weapons can be targeted to alter behavior (see Box BBB at p. __). As Fenton said, “If we can deny two or three of these, the terrorist moves from the offensive to the defensive.”

            While admittedly only initial concepts, a variety of non-lethal technologies may have applicability to the defense of airliners against terrorist actions:

iNear term, and predominantly available off-the-shelf:

b Riot control agents; pepper spray.

b Slippery agents (liquid films of such low friction that an assailant cannot maintain his footing).

b Stun guns; Tasers. These do not necessarily have to be in the hands of a pilot or flight attendant (see ASW, Oct. 8, p. 4). Rather, they can be installed in a bulkhead, on the floor, and so forth.

b Obscurants; malodorants. The former includes smoke, the latter includes strong odors sprayed into the area, such as the smell of fecal matter or decaying flesh. “You start to gag, try to resist breathing” when exposed to these strong odors, Fenton explained.

b Entanglement. This approach involves the use of a net that would suddenly deploy, entangling assailant(s).

b Dazzlers. High-powered strobe lights would dazzle the assailant, creating a strong instinctive desire to shut the eyes.

b Audible acoustics, sirens. These devices would emit a random, high-pitched piercing noise.

iMid Term (considered 3 years +): Calmative/sleep agents. A calmative agent, similar to the medications to relax patients before surgery, could be sprayed, nullifying the assailant’s aggressive behavior.

            Fenton explained that more than one technology might be applied (see conceptual illustration CCC at p. __). For example, smoke could be used to deny the sense of sight. Currently available smoke generators “can fill the entire cabin of a 747 within seconds,” he said.

            The random high-pitched shrieks of sirens, he said, would deny the sense of hearing. In the presence of this piercing noise, terrorists would be unable to communicate.

            Should a terrorist in the smoke and shrieking noise stumble on a stun gun now activated and ready to fire, the jolt of electricity would drop him to the floor.

            In this scenario, the sense of smell and hearing would be denied, motor skills would become spastic, and probably in the face of all this, one’s ability to think, the all-important cognitive skills, would be reduced to a jumble of instinctively protective reactions.

Everybody goes down

            The thought-provoking concept suggests that non-lethal weapons would affect everybody in the cabin – passengers from 5 months to 85 years old, as well as the terrorists. That may well be too aggressive an approach. In this whole-cabin concept, any sky marshals aboard would be incapacitated as well. So would the flight attendants. On this score, one should remember the flight safety role played by flight attendants. If people have been wounded or the aircraft damaged in any terrorist-subjugating melee, the captain doubtless would divert to the nearest airfield. In this case, flight attendants incapacitated by non-lethal gas, for instance, may be in no condition to perform their vital role in providing first aid and/or preparing for an emergency evacuation upon landing.

            Knowing that non-lethal devices might be triggered to incapacitate everyone in the cabin, many potential passengers would be dissuaded from flying. The impact of strobe lights, shrieking sirens, and so forth, on the aged, the infirm, the asthmatic, the heart-attacks waiting to happen, might well be unacceptable. Triggering the full panoply of non-lethal weapons in response to the actions of a mentally disturbed passenger, or one whose behavior has been affected by illness, or in response to a fit of air-rage might well be an over-reaction leading to embarrassing media exposure if not significant legal liabilities.

            The use of smoke as an anti-hijacking ploy may be counterproductive for a number of reasons. Yes, it would deny the assailants’ visibility, but it also would deny any sky marshal(s) the ability to see and act effectively. It seems likely that smoke would quickly enter the cockpit, as even an armored door would be vented to handle depressurization. In this event, pilots would need some way to evacuate the smoke, or to physically displace it, such as with the Emergency Vision Assurance System (EVAS). This emergency equipment item is finding its way onto more aircraft to help pilots see instruments and out the viewscreen in the presence of thick smoke in the cockpit from such things as electrical fires, air conditioning system failures, etc. (see ASW, July 30, p. 6). Indeed, hijackers/terrorists have used smoke devices in previous incidents; smoke as a defensive response also can be used as an offensive weapon (see related p.__ brief).

Not everybody goes down

            For these reasons, a more limited approach to the use of non-lethal technology may warrant consideration. In this more restrictive approach, a so-called “security zone” might be established on the cabin side of the cockpit door, extending back about 3-4 feet. Should terrorists try to penetrate this zone, they would be subjected to, say, slippery agents on the floor to negate their footing, an entangling net that would drop from the ceiling, dazzlers, perhaps an electrified door and bulkhead that would provide an incapacitating jolt on contact.

In any event, the trade off’s would require thorough analysis. To this, Col. Fenton heartily agreed. “You have to Red Team it,” he said, referring to the need for an independent evaluation of all aspects, positive and negative, involving the use of non-lethal weapons in the cabin of a jetliner. Indeed, a rough-cut Red Team approach lays out many of the positive and potentially injurious factors involved (see table DDD at p.___).

            In the near term, efforts to prevent potential terrorists from boarding in the first place, and a hardened cockpit door to bar entry, seem the most prudent and effective near-term actions. Q

BOX p. 1

Non-Lethal Weapons Aren’t Guaranteed ‘Not Lethal’

The official definition of non-lethal weapons:

“Weapons that are explicitly designed and primarily employed so as to incapacitate personnel or materiel, while minimizing fatalities, permanent injury to personnel, and undesired damage to property and the environment.” (Emphasis in original)

Source: DoD Joint Non-Lethal Weapons Program


The ‘Target Set’ for Non-Lethal Weapons

8The 5 senses:

            ţ Smell

            ţ Taste

            ţ Feel

            ţ Hear

            ţ Sight

8The capabilities:

            ţ Cognition

            ţ Motor skills

Source: Joint Non-Lethal Weapons Program


Non-Lethal Technology Concepts

Half-page illustration of B747 here

Caption: Above, an array of non-lethal technologies that could be employed to incapacitate assailants. Because everybody else would be incapacitated, these conceptual applications might be restricted to a “security zone” immediately aft of the cockpit.

Source: DoD Joint Non-Lethal Weapons Program

Table DDD

The Non-Lethal Anti-Hijack Armory

10,500 jobs go at Boeing (oct 15th, 2001)

Boeing this afternoon confirmed plans to axe 10,500 jobs within the next two months.

The US aircraft maker has been hit by the downturn in airline business since the 11 September terrorist attacks.

Demand for new aircraft has been dramatically reduced. Hundreds of passenger aircraft have been taken out of service as airlines scale back their services because people are more reluctant to fly.

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