Strobe light frequencies

[Haraka]

A friend of mine has been presented with some night video of what he thinks was a Hercules or Transall over Europe . To possibly help determine which of them it might have been he counted the strobe rate of a " red light " .

Apparently the video shows a red strobe light on the aircraft which displayed at about 132 strobes per minute (2.2 Hz). He cannot find any document on standard frequencies for such strobe lights and only found that "generally, the rule for a plane is between 40 and 100 strobes per minute".

Anybody able to comment?

[tucumseh]

Def Stan 00-970

The flash frequency for any single light source
shall not be less than 40 cycles per minute. The
flash frequency shall not be more than 100 cycles
per minute except when the system includes
overlaps created by more than one light source.
In overlaps, the effective flash frequency shall
not exceed 180 cycles per minute. The effective
flash frequency is to be established as that
frequency at which the aeroplanes complete
anti-collision light system is observed from a
reasonable distance.

[Haraka]

Many thanks indeed Tucumseh, I have suggested that it might possibly be two lights seen as being close together :)