Formation Go

By lex, on December 18th, 2010

Military aircraft typically fly from point to point in formation. The two-ship formation offers mutual support for the minimum tactical aviation element while reducing the burden of gaining individual flight clearances. It also permits an efficient use of airspace and provides an opportunity for leadership; a senior aviator often serves as mentor for his more junior partner.

There are essentially two classes of formation take-off: The first involves a “running rendezvous,” wherein the leader will launch independently and his wingman will follow him after a short interval of between eight and ten seconds. The lead can use full power for takeoff, will capture an agreed upon rendezvous airspeed at reduced power, and allow his wingman to use his excess power to close. In the FA-18, we typically rejoined at 300 knots, with the wingman using 50 knots of excess airspeed for closure until reaching 500 feet in trail, reducing that number by 10 knots at each hundred feet until snuggling up tightly aboard. Once his “parade” formation is assessed as adequate, the lead will either shake his wingman by thumbing him back into a more relaxed “cruise” formation, or else push him into combat spread: 3000-5000 feet of horizontal separation and roughly co-altitude in controlled airspace, and a little wider with additional vertical separation tactically.   Combat spread formations offer good visual mutual support, allows a wingman to efficiently operate his weapons systems while reducing the airmanship burden of close formation management – parade requires excruciatingly precise control inputs and the wingman’s complete attention. But whether it be in parade or offensive combat spread, close or far, the first and most important responsibility of a wingie is to not hit his lead. One of my first COs briefed mission priorities thusly: First, don’t hit me. Second, maintain sight of me (because losing sight makes it possible to break the first rule). Third, everything else.

The running rendezvous is a little safer than a formation take-off, wherein the two-ship element matches power settings on the runway and launches in parade formation: In the running rendezvous there is only one piece of high speed, carbon epoxy enwrapped titanium (bearing fragile human tissue never architected for the purpose) hurtling down the strip at a time. Each aviator can pay full attention to his machine in a critical phase of flight. And if the lead is forced by mechanical difficulty or other misadventure to execute a high speed abort prior to takeoff, his wingman will barely be rolling and can easily stop; this averts the potential for the greatly undesired formation rendezvous in the departure end arresting gear. Some runways are insufficiently wide for two aircraft to takeoff side by side and still ensure deconfliction if the flight lead aborts.  And a formation take-off requires the lead to use something less than full power to ensure his wingman can keep up – at high density altitudes and heavy weights, he might just want all of it.

The formation take-off is a better way to launch in conditions of reduced visibility (although not at night) or with a low ceiling that might preclude a rejoin prior to entering the clouds. But even more importantly, the formation go looks better, and – as we ought to know by now – it’s better to die than look bad.

With takeoff clearance in hand the lead will taxi to the downwind side of the runway to ensure that his wingtip vortices are swept away from his wingman’s aircraft. The wingie will taxi alongside into parade formation; typically down a 45 degree bearing line – in the Hornet, this position is judged by taxing forward until the leader’s wingtip missile launching rail is lined up with the lead’s helmet. Having established the correct bearing line on his side of the runway, the wingman then judges fore and aft distance by “squaring off” the trailing edge of his lead’s exhaust pipes, thus completing the triangular formation geometry of bearing line, nose-to-tail and distance abeam.

When he’s ready to go, the flight lead will raise a hand on the wingman’s side of his canopy and whirl a two finger “turn up” signal; both pilots will run their engines up to 80% power, quickly rescan their takeoff checklist, check their engine gauges for normal operations and ensure that there are no warning or caution lights illuminated. The lead will give his wingie a look-over to ensure he is in the proper configuration for takeoff – stabilator trim and flaps set, canopy down, nothing leaking or spewing. When he’s satisfied with his machine the wingman returns the favor, signifying with a “thumbs up” that he and his aircraft are ready to go, and that lead’s aircraft looks good too.

Satisfied, the lead will raise his non-throttle hand vertically and lower it in a karate chop motion. The speed of this motion varies from flight lead to flight lead: Some will attempt to lower their arm at a pace approximating the throttle up, others will eschew such niceties in favor of unambiguity. The important thing is for lead to pick a power setting and stick with it, eliminating at least one variable.

Most takeoffs in the FA-18 are accomplished in afterburner – it uses a little more gas, but is more expeditious from throttle up to up and away flight, which gets the airplane quickly out of the “poorly designed tricycle” regime and into its natural element. Most leads will shove the throttles through the afterburner detent to the firewall before backing off about half way to the detent again. This allows the wingman some excess power with which to maintain position, while keeping him from having to cycle in and out of blower, surging and falling back back and generally looking like ass. Because it’s crucially important not to look like ass in front of knowledgeable spectators, such as those commonly found around airfields. So crucial, in fact, that the wingman may break his vow of administrative silence over the radio to urge “Power” if his lead is too far back on the throttles, or “Gimme a couple” (percent RPM) if he’s too far up.

There’s not much time to scan the engine instruments for malfunction indications while picking up speed 40 feet away from another accelerating fighter in full grunt, but form dictates a quick head bob off the leader’s launcher rail and into the cockpit long enough to ensure that nothing is actually on fire that oughtn’t be, and that – at a minimum – both exhaust nozzles are entirely open, indicating a good light of the afterburners.

If the lead is forced to abort straight away, the wingie has the option to carefully clear forward and gradually bring his airplane to a stop, but with any kind of speed on the machine he’s better off to throttle up and keep going for takeoff. The worst case is a dual, high speed abort, which – thankfully – hardly ever happens. Airplanes are meant to fly, and at full gross weight, they are often resentful of maximum performance braking from high speeds. The rule in a dual high speed abort was, “First guy to the arresting gear has to pass it up,” at which point the second pilot will lower his hook to engage the gear while the first gets to explore the off-road capabilities of a 40,000 pound fighter while saying a brief prayer to the god of Martin-Baker.

Should no evil thing arise, the lead will raise his throttle hand at a 45 degree angle to the vertical, and push it back and forth twice, indicating to his riveted wingman that the jets are almost at flying speed. His left hand will go back atop the throttles, where it will stay for the rest of the flight. At about 140 knots the lead will smoothly bring the stick about half way back, the wingman matching the movements of his lead’s stabilators. Twenty-five knots or so later, the two aircraft will reach nosewheel liftoff speed and the real formation “flying” begins. A single head nod from the leader will indicate “landing gear and flaps up”. The considerate flight lead may shortly thereafter throw his head back towards his ejection seat headrest indicating that he is coming out of afterburner to prevent his wingie from surging forward at the sudden thrust differential.

The whole process takes about seven or eight seconds from karate chop to gear up.

 

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1 Comment

Filed under Best of Neptunus Lex, Carroll "Lex" LeFon, Carroll LeFon, FA-18, Flying, Lex, Naval Aviation

One response to “Formation Go

  1. Pingback: Index – The Rest of Neptunus Lex | The Lexicans

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