Aeronautical Charts "FI" identification beacons

[ScottBouch]

Hi all,

What does "FI" stand for?





I used to volunteer at Cranfield on the Lightnings there, I recall a green flashing lamp on the roof of a building flashing away Morse code at night; is this the identification beacon referred to here?

This lamp was like an upturned bin, of a translucent green material, with a bright lamp inside. I imagine there may be a few types out there.

I found this online which may be related to the FI notation: https://ppltutor.com/air-law/signals...ation_beacons/ but any advice on this is welcomed!

Cheers, Scott.

[pba_target]

Originally Posted by ScottBouch

Hi all,

What does "FI" stand for?





I used to volunteer at Cranfield on the Lightnings there, I recall a green flashing lamp on the roof of a building flashing away Morse code at night; is this the identification beacon referred to here?

This lamp was like an upturned bin, of a translucent green material, with a bright lamp inside. I imagine there may be a few types out there.

I found this online which may be related to the FI notation: https://ppltutor.com/air-law/signals...ation_beacons/ but any advice on this is welcomed!

Cheers, Scott.

You've got it - night visual ident beacon for the airfield is a large light flashing a Morse ident. A bit like the old letter identifiers that had to be laid out horizontally for daytime VFR. Essentially useless in the 21st century though!

[ScottBouch]

Thank you! Yes, this is of retrospective interest / research!

So the remaining question is can anyone find what the initials "FI" stand for?

I'm tempted to make an obvious assumption here, but am going to put that aside in anticipation of correct confirmation, as we all know what ASSUME stands for!

Many thanks, Scott.

[pba_target]

Originally Posted by ScottBouch

Thank you! Yes, this is of retrospective interest / research!

So the remaining question is can anyone find what the initials "FI" stand for?

I'm tempted to make an obvious assumption here, but am going to put that aside in anticipation of correct confirmation, as we all know what ASSUME stands for!

Many thanks, Scott.

Could well be F-L, my exaggeration, to describe a flashing light. That's certainly how light houses (those that were flashing not occulting) were annotated, though those included the flash pattern.

[MPN11]

I''m tempted to offer "Fl" with the L in lower case, as in 'flashing'. [oops, beaten to it!] That annotation on charts seems to apply to all locations in UK with the famous "Pundit", regardless of airfield designator ... https://en.wikipedia.org/wiki/Pundit_Beacon

[ShyTorque]

Flashing Ident.

[charliegolf]

Originally Posted by ShyTorque

Flashing Ident.

Yep. We used to learn that sh1t in the last century, eh Shy?

CG

[ScottBouch]

Thanks for the info on Pundit Beacons! Every day's a school day.

So it's either FI for Flashing Ident, or Fl for Flashing.

I knew this wouldn't be straightforward!

[ShyTorque]

Originally Posted by charliegolf

Yep. We used to learn that sh1t in the last century, eh Shy?

CG

We did, but it was obviously SO last century..

[ORAC]

Doing a bit of digging, and via admiralty charts, it would appear to be an international standard…..

https://en.wikipedia.org/wiki/Light_characteristic

[Professor Plum]

It stands for “F**king Interesting”

There have been many a night where I’ve been tooling around, and decided to look out the front window to see a flashing beacon at an airfield.

“Thats F**king Interesting” thought I.

On landing and checking the charts legend, my suspicions were confirmed.

[ScottBouch]

Originally Posted by Professor Plum

It stands for “F**king Interesting”

There have been many a night where I’ve been tooling around, and decided to look out the front window to see a flashing beacon at an airfield.

“Thats F**king Interesting” thought I.

On landing and checking the charts legend, my suspicions were confirmed.

I love that!

[ScottBouch]

Originally Posted by ORAC

Doing a bit of digging, and via admiralty charts, it would appear to be an international standard…..

https://en.wikipedia.org/wiki/Light_characteristic

Thank you, so according to that Wiki page, it is Fl for Flashing. Confirming MPN11's original post.

I'm glad I didn't go with my assumption of Flashing Ident! Knew I'd be wrong.

Many thanks all! Questions answered, and a laugh on the way!

Cheers, Scott.

[Andrewgr2]

I seem to recall that in the post war period when there were lots of airfields and relatively little street lighting pilots flying at altitude on clear nights could see dozens of Fl beacons at any one time. Can anyone confirm?

[chevvron]

Originally Posted by Andrewgr2

I seem to recall that in the post war period when there were lots of airfields and relatively little street lighting pilots flying at altitude on clear nights could see dozens of Fl beacons at any one time. Can anyone confirm?

Still happens Fl green for civilan and Fl red for military airfields; these are called 'Ident Beacons' as they flash a 2 letter code in morse.
Seldom used in the UK but an Aerodrome Beacon (ie no ident) flashes either alternate white/green (civil) or alternate white/red (military). If you ever fly over New York in the dark, you will see literally dozens of the white/green ones.
Smaller civil airfields in the UK are allowed to display a flashing white strobe light during their hours of operation but in this case, there must be no other strobe within about a 10nm radius to avoid confusion as there is no ident with this system, it's just for location. Typical examples of these are Fairoaks in Surrey and about 10 miles away, Blackbushe in Hampshire.
One final one, there is a solitary 'lighthouse' which is operated by Trinity House which flashes white. Back in the '30s, many airfields had this, Croydon being one; the last one operating as far as I know is at RAF Cranwell, on the top of the College building some 30 odd miles from the sea but observable from ships off the coast.

[MENELAUS]

I think most US airfields ( O’Hare certainly has ) still have the rotating airfield beacon (white with a horizontal beam….think the closing scenes in Casablanca in the fog ! ). Quite what use their are these days lord knows.

[MPN11]

Nostalgia moment ... at RAF Strubby in the 60's, driving around the airfield to turn off the Pundit when night flying finished [around 0400 on a bad day!]. And if the fog had rolled in from the coast, getting lost on my own airfield!

[NutLoose]

Do they still use the cloud height lights, Odi used to have one next to the gliding club building. one vertical and one that used to run up and down the vertical beam to triangulate the height..

[SASless]

In the United States......

1. Airport/Heliport Beacons

   1. Airport and heliport beacons have a vertical light distribution to make them most effective from one to ten degrees above the horizon; however, they can be seen well above and below this peak spread. The beacon may be an omnidirectional capacitor-discharge device, or it may rotate at a constant speed which produces the visual effect of flashes at regular intervals. Flashes may be one or two colors alternately. The total number of flashes are:
      1. 24 to 30 per minute for beacons marking airports, landmarks, and points on Federal airways.
      2. 30 to 45 per minute for beacons marking heliports.
   2. The colors and color combinations of beacons are:
      1. White and Green- Lighted land airport.
      2. *Green alone- Lighted land airport.
      3. White and Yellow- Lighted water airport.
      4. *Yellow alone- Lighted water airport.
      5. Green, Yellow, and White- Lighted heliport.NOTE-
         
         *Green alone or yellow alone is used only in connection with a white-and-green or white-and-yellow beacon display, respectively.
         
   3. Military airport beacons flash alternately white and green, but are differentiated from civil beacons by dualpeaked (two quick) white flashes between the green flashes.
   4. In Class B, Class C, Class D and Class E surface areas, operation of the airport beacon during the hours of daylight often indicates that the ground visibility is less than 3 miles and/or the ceiling is less than 1,000 feet. ATC clearance in accordance with 14 CFR Part 91 is required for landing, takeoff and flight in the traffic pattern. Pilots should not rely solely on the operation of the airport beacon to indicate if weather conditions are IFR or VFR. At some locations with operating control towers, ATC personnel turn the beacon on or off when controls are in the tower. At many airports the airport beacon is turned on by a photoelectric cell or time clocks and ATC personnel cannot control them. There is no regulatory requirement for daylight operation and it is the pilot's responsibility to comply with proper preflight planning as required by 14 CFR Section 91.103.

[BEagle]

Our night cross-country during Jet Provost basic training included a 'pundit crawl'. But in those days there were considerably more RAF aerodromes in existence....

One of the jolly japes played on new lads working in the ATC tower was to "Take a cup of tea over to the chap in the pundit", who was described as having a lonely existence tapping out the ident with his morse key. The poor lads would wander round the pundit trying to find the door until the penny dropped!