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1/14 So picking up on from this thread on air policing, let's start to look at what an air policing package involves.
To intercept an aircraft, first you have to know roughly where it is. Maybe you get a handover from a NATO country further north or... @cathalberry @GCraughwell https://twitter.com/_IDFOC/status/1332996121749229571
To intercept an aircraft, first you have to know roughly where it is. Maybe you get a handover from a NATO country further north or... @cathalberry @GCraughwell https://twitter.com/_IDFOC/status/1332996121749229571
2/14 ...maybe the aircraft is coming from another direction and you need to find out for yourself where they are. So let’s talk about radar. @IRLDeptDefence @IRLDeptPER @RACO_DF @ARCOIreland @DefenceIreland @slandail_nssi @kevpipps @tchukstr @DFPRB @Edward__Burke @wrafter_colin
3/14 We all know the scenes in the movies of the intense air traffic controller hunched over a screen of dots surrounded by little tags of information, skilfully talking down the damaged or lost aircraft to a safe landing. @nealerichmond @lichamber @SorcaClarke_TD @MattShanahanTD
4/14 All that information on the screen, the height, the speed and very often the location of the aircraft isn’t coming from the radar on the ground, it's coming from the aircraft’s transponder. @malcolmbyrne @MarkWall1 @CllrPioSmith @lawlessj @davidstantontd @GaryGannonTD @yfg
5/14 This is Secondary Surveillance Radar and is what air traffic controllers the world over use to direct aircraft around the place. However, it relies on the aircraft telling you everything about itself. Turn off the transponder, there's no information and or dot on the screen.
6/14 What we all usually think of as ‘radar’ is called Primary Radar. This is different in that it sends out pulses of radio waves, which bounce off an object and return to the antennae telling you where the object is, as a dot without any other information on your screen. @donlav
7/14 Primary radar has its limitations over distance, however, being subject to physics just like everything else. From ground level, the radio wave you transmit will eventually meet the horizon and head off into space... @BrendanSmithTD @mickthehack @obraonain @JohnMooneyST
8/14 ...Anything above that horizon you can still see, anything below that horizon is invisible. Nevertheless, it’s the primary means of detecting non-cooperative traffic globally. @CormacJOKeeffe @Aiden_Corkery @seandanaher5 @KennethMcDonagh @RuthMCasey @LauraMcGonigle @FineGael
9/14 Some countries overcome the horizon problem either by putting more fighters into the air (a costly proposition, especially if there’s nothing out there that day) or by using Airborne Early Warning (AEW ) aircraft. @dsmooney @ConorHogarty @TomClonan @siegejadotville
10/14 These are basically primary radars and an air traffic control unit taken into the air on a converted airliner/ cargo plane / business jet. Still costly, but cheaper than an extra squadron or two of fighters. @DavidBa8976 @PeterOHalloran1 @ahernegerald @beaufortcomment
11/14 To illustrate the above, imagine yourself in a dark basement trying to direct your friends around the room. The game is that anyone who bumps into anyone or anything else loses. Secondary radar is when all the players hold a light up – everyone can see where the others are.
12/14 You can now control them around the room and keep everyone in the game. But, one player doesn’t have a candle and is walking through the middle of everyone anyway. You turn on your Primary radar, in this case a flashlight that you shine around the room.. @jjsalmo @galwaygrrl
13/14 ...positively identifying where everyone is. There are a few boxes at the back of the room that you can’t see behind though. This is your radar horizon. Your AEW is someone standing at the top of the stairs turning on the light switch... @liamhayeslabour @SeanFionn
14/14 ...and now everyone is visible. Ireland, needless to say, does not have a primary radar capable of the distances we are talking about here although it is the most basic part of the air policing package... more threads to come. (With thanks to @declan275).
