Are photochromic lenses suitable for flying?
The UK CAA gives some pretty good guidance on sunglasses for aviation. However, we’ve noticed that there is an area of confusion within the pilot community about photochromic sunglasses.
Obviously if your sunglasses ‘are un-tinted when un-activated and rely on UV light to activate they will obviously be of no use as a sun lens on the flight deck as there is unlightly to be enough UV to cause them to activate on a commercial airline flight deck.
Yes, Bigatmo photochromic sun lenses are suitable for flying. Our Alutra copper-brown photochromic lenses are activated by UV light and are designed to operate through a specific light transmission range and are already set at the optimum tint level for flight deck use in their un-activated state. Depending on what you are flying (or driving), there will be more or less UV light in the environment. For example, only a small amount of UV penetrates the windscreens of an airliner flight deck, whereas quite a lot might enter the cockpit of a light aircraft with a bubble canopy. The photochromic element activates, and the tint will vary through a specific range depending on the level of UV it is exposed to. This makes them suitable for virtually every situation and not just the flying.
In the case of the commercial flight deck, our lenses should not activate and the light transmission rate is set to allow you to read the instrument panel in high contrast situations, such as flying towards a sunrise. (You’ll still need to use the visors as nobody should be looking directly at a rising sun!) In the case of the bubble canopy, the ambient glare and UV are likely to be higher and the instrument panel is likely to be brightly illuminated, in which case the lenses will activate. You will almost certainly not notice this happening but you’ll be pleased that it has.
There is quite a lot of misleading information relating to old technology photochromic spectacles and the potential problem of moving from a bright environment to a dark one, rendering the wearer unable to see clearly. In real life, I’m not sure where this change from light to dark might occur – when entering cloud it can often appear brighter, anyway, it’s just not a concern. We spent eighteen months developing this lens and I would estimate that there have been well over a million hours flown in them, without any issues.
You might have noticed that we also provide prescription lenses and that you can get a prescription version of our Alutra copper-brown photochromic lens. The prescription version has exactly the same characteristics and can be used in exactly the same way as our plano lenses.
We also provide Transitions lenses to some customers but we don’t recommend them for use as flight-deck sunglasses as they’re not designed for the environment and activation might be unreliable. They’re fine at night though!