Originally Posted by
Mr. Vice
Fighters don't often gain much in fuel efficiency by climbing much higher than the tropopause (normally 36,000 in the UK) there is sometimes benefit in climbing higher in to a jet stream if it is from behind. They do however benefit a great deal from the ability of flying higher than most airliners and thus receive direct track to their requested location.
The F-16 has a mode called Home Mode in which the Modular Mission Computer (MMC) calculates and commands (via display in the HUD) the best climb, cruise and descent speed and the best cruise altitude to achieve optimum range performance with the actual configuration. To make those calculations the MMC receives input from the Stores Management System regarding external stores, (weight and drag), Fuel remaining from the Fuel Management System (weight), air data from the Air Data Computer (pressure and OAT) and wind conditions from the INS or EGI. In a light and slick configurations with only one droptank, the MMC will normally command you to climb to 42-45.000 feet for best range performance once the fuel load is reduced. In heavier and more draggy configurations the final altitude will more likely be in the upper part of block 3.
Formation wise, a 4 ship will normally fly some sort of container formation unless clouds are encountered. In that case the formation will close it up to loose echelon and tighten it up some more if required.
Crossing the pond will normally be done around FL250, since the AR speed is only 310KTS. At this speed and altitude heavy jets might be very close to the backside of the power curve (dry power), so we prefer not to go higher. A single KC-135 will normally tow 4 to 6 F-16's depending on the route. Here we will normally fly loose echelon to fighting wing with up to 3 aircraft on each side of the tanker.
Crossing the pond at FL250, you get to se more ships then airplanes....
PS. I'm pretty sure modern fighters with beefier engines like the Typhoon and F-22 will prefer to climb to mid block 4 or higher to conserve their gas. Maybe some Tiffy or Raptor driver can confirm?