Last week I blogged about a mystery item handed over to me at crew change and challenged you to tell me why my chief pilot purchased these. If I have opportunity to, I will edit this paragraph to mock or commend you on your most excellent guesses. If not, you know I'm busy this week.
The greatest hint to what they were for was not in the photo, but in the title of the blog post "The Future's So Bright ..." Those well-versed in eighties music will be able to complete the line "... I gotta wear shades" suggesting that the gag glasses had been sunglasses. It was the lenses that were of use, not the frames themselves.
You'll remember me complaining about the undimmable digital rpm display on my new high-tech tachs. From the install up until now it was either endless summer in the north, or working low altitudes in mountainous areas, so I had suffered no personal pain from the overbright avionics. The manual includes installation instructions, which recommend it be configured for a permanent backlight. This at least suggests that it could be otherwise configured, and a reader dug out the specification for a part required, which information I have passed on to maintenance. I'd planned to request it more vigourously once I started into the winter night work.
The night work came for this crew and the light from the tachometers was as obnoxious as I had predicted. They couldn't find a source of sunscreen film in the small town, but there was a dollar store and the lenses from the gag glasses filled the bill. They cut them up to create little shields for the displays. The numbers are clearly visible in daylight yet not retina-piercing at night.