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Comment by ttobbaybbob | Hacker News Reader

"Infrared laser energy can pose a hazard to persons on the aircraft"

"affect a flight crew’s ability to control the aircraft"

How would the infrared laser impact the aircraft originating the laser (i assume there's no way the laser would be pointed at the aircraft its mounted on)?

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Basically, the safety analysis will have to show that it the risk to people on-board is mitigated. Ways the risk can be realized are basically by reflection -- even secondary and tertiary reflections of infrared lasers can be dangerous, since the beam energy is quite high and the blink reflex isn't triggered. Concerns would be things like glancing reflections off water, reflections off buildings, etc. Posssible mitigations would include having an independent monitoring system disable the laser if it would intersect the ground (likely required to mitigate hazards to people on the ground anyway), IR notch filters on the windscreens to prevent reflections from entering the cockpit (or laser safety glasses required in situations where it may be used), etc. This is generally the aviation mindset -- a rigorous exploration of what can go wrong (and sometimes, the answer is "not much", but even that needs to be considered and quantified) with multiple layers of mitigation to get the risk to acceptable levels.

Why is the blink reflex not triggered by these reflections?

Because we don't see in infrared.

> A pop or click noise emanating from the eyeball may be the only indication that retinal damage has occurred i.e. the retina was heated to over 100 °C resulting in localized explosive boiling accompanied by the immediate creation of a permanent blind spot

Terrifying stuff https://en.m.wikipedia.org/wiki/Laser_safety

Curious if you could do this quick enough via a simple detector in the cockpit. Is there a time interval that is short enough that the laser has basically no chance of harm?

In terms of time constants: Yes, probably. Visible lasers can be eye-safe at much higher powers because of the blink reflex, and the blink reflex is on the order of a hundred milliseconds -- detecting IR and shutting down even a gas laser should be millisecond-scale at most. One challenge would be very specular reflections that hit an eye but not your sensor, but a wide-area sensor should be able to get reflections even off the pilot's eye itself. The remaining bit would be very high frequency specificity on the sensor to allow high sensitivity without false positives, but that's pretty trivial.

That's all very well, but surely you'd only turn the enormous laser on if there were a heat-seeking missile bearing down on you, in which case the laser represents the safer option even without any risk mitigations.

You'd only turn it on if your sensing system had a positive detection for a missile... any such system has its own failure modes, and while it's true that a sensing system with few false positives is a mitigation to hazards to the pilots, you have to consider the system as a whole. Especially if heat-seeking missiles fired at cargo planes are rare (and from what I can tell, they are), you expect the majority of activations to be false positives.

"Please turn off all cell phones and other electronic devices, including energy weapons."

It could bounce back from a reflective surface somehow and hit a cockpit or cabin window, though you'd need to be flying really low or at an unreasonably steep angle to be concerned about that. They're probably just trying to cover all possible bases though.

They could be implying its an all-aspect jammer which is effective against air to air missiles while only verbally discussing the ground threat.

Civilians always think of ECM and jamming like a smooth omnidirectional output, yet it seems to me pretty obvious a kaleidoscope like randomish distribution would work much better as a jammer, so they have to assume that 0.00001% of the time the entire laser beam might hit water and reflect right back into their eyes. I suppose a REALLY smart AI controlled jammer could actively control its jamming signal to never output power in a direction that would reflect back at the plane, which would probably shimmer at like 10000 Hz as the plane wiggles thru the sky, so on average the plane would be well protected.

You know its a REALLY bad neighborhood if they try stealth technology to defeat incoming radar guided missiles. That's really hard core air transport operations.

Kind of makes you wonder if "ufo sightings" aren't air force stealth air transport vehicles. AFAIK there are no unclassified stealth air transport vehicles, but you'd think that would be terribly useful if you don't have total air superiority so either us or the Russians must have at least blueprints somewhere for something like a B-2 that can carry people and/or a tank or two. Or maybe fedex will restart the B-2 production line...

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