E3 Sentry Question

[Dan Gerous]

Heading back to work after lunch, I saw the distinctive large arc contrail remains of an E3 orbiting over the Borders, and sure enough, following the curve I saw it, just as it started to trail again. A couple of things I pondered over, that you guys may be able to answer. Is there an "orbit switch", that sets the aircraft up in a pre-planned orbit, or does it have to be flown manually? Everytime I have seen these over the Borders, apart from once, they are always in a right hand, (clockwise), turn. I always thought that the Captain of an aircraft, sat in the left hand seat and therefore it should be in a left hand turn/orbit, as the Captain is in charge and would need to see where the aircraft was heading. So why do the E3's, that I've seen anyway, go round in a right/clockwise turn?

[Just This Once...]

Aircraft can orbit either left or right. Either pilot can be the handling pilot but captain is usually, but not always, in the left hand seat. Autopilot has a green rating so does most of the work. Orbits orientated to get the most out of the radar system, or to get the sun out of the captain's eyes.

Many tricky decisions to make on the E-3 flightdeck, but all the time in the world to make them.

[FATTER GATOR]

Many tricky decisions to make on the E-3 flightdeck, but all the time in the world to make them.


..Tea or coffee?

..Sandwiches now?

..Sit down to pee....?

[Dan Gerous]

Thanks JTO. Heard what I thought were Typhoons, over the factory around the same time as the E3 was in the area, but they were gone by the time I got outside for a look.

[Willard Whyte]

So why do the E3's, that I've seen anyway, go round in a right/clockwise turn?

If there is a one way airway nearby then some orbits are mandated to be cw/acw, as appropriate, so a/c are not going head to head.

The route to the orbit will have an effect. For example, ATC vectors or mandated routing prior to the join may lead to a smoother entry in one or the other direction.

Other than that? Sun position, toss of a coin, how the crew feels on the day. Does the nav prefer to sleep with head forward (lh orbit) or head back (rh orbit).

The rumour that half way through a sortie it needs to switch direction to 'unwind' is completely unfounded. Allegedly.

[Vzlet]

Of course, a clockwise orbit produces several extra radar scans an hour. ;)

[Dengue_Dude]

Surely that's only in the Northern Hemisphere . . . :ok:

[Fox3WheresMyBanana]

Had an AWACS trip to see how their side of the game worked. Orbit direction was preplanned (not sure why, think it was proximity to controlled airspace vs likely main threat direction). Orbits were free-flown every so often for pilot handling practice - they even let me do one. Lots of anticipation needed, like leading a formation really.

[Halton Brat]

Perhaps it's all down to the Gyroscopic Torque Reaction of the radar scanner...............

HB

[fingureof8]

The right hand orbit is the is infact the orbit of choice for the nav. It allows him to slump back in the nav chair, thus getting a better qualtiy of sleep:zzz:! Until of course the question of tea or coffee and when to put the cumberland sausage breakfast in the oven.

[fingureof8]

F&^KIN& cut backs!!!

[Willard Whyte]

The right hand orbit is the is infact the orbit of choice for the nav.

Thing is I preferred the slumped forward pose - cold wx jacket on desk as a pillow of course. If I lolled backwards I was always liable to snore, which would wake the poor engineer.

[Willard Whyte]

Orbit direction was preplanned

I always used to say certain members of the E-3 fleet couldn't take a dump without a plan.





(Apologies to Tom Clancy)

[Green Flash]

Well they were certainly covering some sky as the north end of the orbit was over Carrbridge!

[Willard Whyte]

UK9 perhaps.

Or a serious ****-up if they were meant to be in UK5

[APG63]

DG, don't listen to any of them. This is the wrong place for serious advice. Let me help you out. It is purely a comfort thing that comes down to being left or right handed. Most captains are right handers, hence most orbits to the right.

[Willard Whyte]

Serious advice already given. Time to lighten up afterwards.

[APG63]

Erm, I think I may have f***ed up here. I don't actually know the reason, I was hoping my answer would have been misleading, but believable. A real bu**er if I stumbled across one of the real reasons by mistake!

I'll get my coat...

[Wensleydale]

Actually its all to do with the effect of changing groundpeed and angles of bank caused by the prevailing wind velocity at height with respect to the radar CFAR circuits and the orientation to the working areas.

Not that you would expect one of the pilots to understand that.... When this used to be taught to the new Sentry crews in the days of yore, the pilot instructor on Sentry Training Squadron refused to send his students because "we have already studied met at basic flying training". Sad but true!

[Biggus]

That "groundpeed" sounds like a tricky concept to understand too....!




Or is it all to do with going to the toilet before you get airborne??? ;)

[Courtney Mil]

Change of heart. Hanging coat back up. I like my answer better. At least we could understand it. What was the middle bit again, Wensleydale? ;)

[Fortissimo]

I think we all understand that groundspeed will change with relative wind direction. The autopilot will try keep you on the same groundtrack in the orbit and so will alter the AOB to achieve that, albeit we are only talking small angles here. When the AOB is higher, more of the beam is being pointed at the ground (= clutter) and so you might occasionally want to have the higher AOB, more cluttered picture occur at (eg) the west side of the orbit rather than the east so that the best picture is available at the range from the orbit that is most suitable for the trade, which therefore means a decision on left or right! Or maybe use one of the other pretty patterns available through the GINS. Either way, it is not going to spill the coffee unless you get the airspeed badly wrong, when coffee spills are the least of your problems (pace Air France).

Also, the QFI/staff chap was right. You shouldn't need a met lecture to remind you that the wind blows up there, which really would be sad...

[Willard Whyte]

Erm, I think I may have f***ed up here. I don't actually know the reason, I was hoping my answer would have been misleading, but believable. A real bu**er if I stumbled across one of the real reasons by mistake!

I'll get my coat...

Sorry, I'm a bit slow on the uptake today. Normal humour detection service will be resumed as soon as possible.

[radar101]

Of course, a clockwise orbit produces several extra radar scans an hour.

I reckon 4 more per hour for typical orbits

[Courtney Mil]

Willard, that's always the risk I run when I try to be a smart arse!