Flashing anti-collision lights, also know as strobes on an aircraft can be seen on the aircraft When flying at 36,000 ft during the day with clear skies.

What is their wattage (e.g 1000 watts) since they are so bright?

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    $\begingroup$ This question covers some of what you're asking. It would be very helpful if you would ask only one question at a time, that way we can point you to existing answers without dealing with the mess of "question A answers your point 1 and question B answers your point 2" etc. $\endgroup$
    – Pondlife
    Jun 4, 2018 at 14:14
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    $\begingroup$ Measuring strobe light intensity in watts doesn't make much sense. Watts are a measure of energy per unit time, and strobes are only "on" for a very short time. Second, for most lights, watts tells you more about the heat output than the light. For light output, you're probably looking for lumens. $\endgroup$ Jun 4, 2018 at 23:36

1 Answer 1


Strobes are not measured in watts, pulse style high discharge lights are measured in Watt-Seconds due to the way they operate. Since the strobe is pulsed for a very short time the watt second gives you a measurement more or less equated to the brightness of a bulb of said wattage on for a one second. The FAA mandates the brightness of anticollision lights via their output in candles not watt-seconds or watts as those are somewhat better for comparing power draw than for comparing brightness of lights:

§ 23.1401 Anticollision light system.


(e)Light intensity. The minimum light intensities in any vertical plane, measured with the red filter (if used) and expressed in terms of “effective” intensities, must meet the requirements of paragraph (f) of this section. The following relation must be assumed:

$$ I_e = \frac{\int_{t_1}^{t_2} I(t)dt}{0.2 + (t_2 - t_1)} $$


  • $I_e$ = effective intensity (candles).
  • $I(t)$ = instantaneous intensity as a function of time.
  • $t_2−t_1$ = flash time interval (seconds).

Normally, the maximum value of effective intensity is obtained when t2 and t1 are chosen so that the effective intensity is equal to the instantaneous intensity at t2 and t1.

With the use of LED's the units them selves draw less power than their older halogen gas style counterparts. For example this unit has a 36V 1A input which computes to 36 Watts of power for the strobe (remember P=IV) but clearly conforms to FAA brightness requirements. There are more options here that draw as low as 4 watts for continuous operation but again tells us nothing of the Watt-Second output of the unit. I can not find any units that list a watt/second equivalent for their output.

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    $\begingroup$ Very clear answer, thank you $\endgroup$ Jun 5, 2018 at 0:48

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