Why can't I turn on the EAC?

[flankerzrj]

I load the aircraft in cold&dark.

Then,I start the A10C normally.

But,when I turn on the EAC,

immediately,

the EAC is turn off automaticly.

 

WHY?

[wtfisgoingon]

You gotta let your Nav system finish aligning before you can turn on the EAC.

 

Look for T=4.0 0.8 and above INS NAV READY is flashing. Takes approx 4 minutes if you don't move :)

[oritpro]

You need to wait for the NAV system to finish aligning after powering up the CDU and GPS/INS systems. This takes about 4-minutes. If you switch to NAV mode on the CDU before the alignment process completes then you get to start all over again.

 

The left and right Yaw and Pitch channels on the SAS panel must also be set to ON before EAC can be enabled.

[flankerzrj]

OK,thanks.

I'll try it.

[jeffyd123]

errrrmmmm... wtfisgoingon is 99% right, oritpro is a bit more wrong.

 

When the nav system is done aligning, when the so-called "T" Line reads T=4.0 0.8 and above INS NAV READY is flashing on the CDU,then either moving the plane forward or hitting the "NAV" button on the CDU display will engage the nav system and THEN the EAC will stay on.

 

Take note, if you move the plane (or hit the "NAV" button on the CDU) before the above conditions, the nav system will still work, but it wont be as accurate (the .08 figure is an order of magnitude of accuracy, so if you start moving when this figure is at 7.6 your nav accuracy will be 7.6 times less accurate) You also find the INS NAV Ready message will be there but not flashing.

 

I personally dont see any difference in the accuracy... maybe it isnt modeled.

 

And you must have the "SAS" switches forward.

Edited April 27, 2011 by jeffyd123

[oritpro]

jeffyd123...you're probably right but it seems that the EAC will not enable at all until the NAV system is fully aligned. Thanks for clarifying this.

[fael097]

let me jump on the boat and mention that i can't turn on the autopilot aswell. it needs the EAC to be on, or just need the NAV to be aligned?

[nomdeplume]

Autopilot requires EAC; so does the PAC system for the cannon.

[rob10]

let me jump on the boat and mention that i can't turn on the autopilot aswell. it needs the EAC to be on, or just need the NAV to be aligned?

 

Not sure whether it needs EAC or NAV, but if you are doing and ALT/HDG hold you need to be in near level flight to get it to kick in -- i.e. if you are pitched up it won't turn on (took me a while to figure that out).

[jeffyd123]

re-read my above post... The NAV can be started when the INS NAV Ready message is on the CDU. If its steady, the nav system is in a degraded mode but will work... when the message is flashing, its fully aligned.

 

By EITHER moving the plane forward OR pressing the NAV button on the CDU will engage the nav system and then you can use the EAC (make sure the SAS is on too)

 

 

For Rob10... there are 3 AP modes.

1 - path will level the wings (but not hold heading) and hold the planes climb/dive angle... used a lot after taking off and for attacks.

2 - ALT/HDG will fly level attitude and hold the heading you have

3 - ALT will hold altitude and bank angle... allowing you to orbit

All of the AP modes require you be within certain limits before they will engage... practice will show whats what.

Edited April 27, 2011 by jeffyd123

[arteedecco]

Also note, the EAC is not supposed to be on during landing and I believe for takeoff as well. Will look for thread on this...

 

Reference this: http://forums.eagle.ru/showpost.php?p=1065911&postcount=13

Edited April 27, 2011 by arteedecco

[Spitfire2170]

Im going to give you a big thanks! This helped so much!!!!!!

[bartleby]

Is there a minimum alignment required for NAV engagement?

[BlueRidgeDx]

EAC should be armed in the chocks just prior to taxi, so there's no restriction on it being armed for takeoff or landing.

 

The EAC should not function under the following circumstances:

 

HARS mode active on the NMSP

 

GPS ONLY selected in the CDU

 

INS ONLY selected in the CDU unless the EGI has fully aligned (0.8 nm/hr)

 

BLENDED mode accuracy less than equal to a full INS alignment (0.8 nm/hr)

 

Any SAS switch not ON

 

CADC failure

 

SAS/EAC emergency disconnect lever activated

 

I'm not sure if the GPS/INS ONLY conditions are presently modeled or not.

[Frederf]

They are. I turned the mode from blended to GPS only a while ago and the EAC ticked off.

 

I think the before landing checklist is in error about EAC. You want LAAP off checked but not EAC.

[Sceptre]

I've had the same problem with the EAC, as the instructor doesn't cover everything in the cold start lesson, but now it's working! thanks guys!