Autopilots in Turbulence

[surplus1]

Surplus,

The main problem with the radar on the ERJ is that the dish is too small. Embraer is working with Honeywell on getting a bigger dish put in. The problem is that the nose is so skinny that it makes it difficult to put a bigger antenna dish in there. I've had nights where we flew right into a cell that the radar said wasn't there only to be unpleasantly surprised. There have been some improvements made to the radar, but there is still a lot of work to be done.

Thanks SD. Now I understand. It's also a different brand from the E120. The early CL-65 had essentially the same problem. They've improve it considerably.

The main problem with the autopilot is that it isn't aggressive enough when it intercepts the localizer. In a lot of instances it will fly right though the localizer and have to correct itself to recapture the localizer.

OK, understood. Couple of questions if you have time. 1) What sort of intercept angles and speeds are you using when in the approach mode? 2) Do you know if the "pots" were adjusted at the airframe factory, by the manufacturer or by your avionics department?

I'm just curious and trying to see if I can learn the cause.

 

[bayoubandit]

Surlpus,

I know you were directing your questions toward Saluki, but if I might intrude. The ERJ has the Primus 1000 and it has proved itself worthless especially on approaches. I found the A/P did fine enroute, except for climbing/descending in speed hold. It would chase the speed badly.

As far as intercepting the loc., at a 30 degree intercept at 180KIAS, the autopilot would consistently overshoot the localizer. It also did an aweful job of tracking. It would bracket the course, in a good crosswind, in really chased the loc and I've seen it where it wouldn't even hold the loc.

If you chose to hand fly, the flight director gave the same commands and would have you chasing the needles as the autopilot would.

Shooting an approach to mins. was usually interesting when you followed the F/D. The autopilot has made me uncomfortable more than once on those low approach days.

 

[Saluki Dawg]

DITTO on everything that Bayou Bandit just said. Well done.

 

[surplus1]

Bayou Bandit & SD,

Thanks guys, I appreciate it. I'm not familiar with the Primus 1000. What you describe doesn't sound "comfortable" at all. Is the system CAT II certified?

Is that an ARINC or a general aviation system? Who makes the autopilot/flight director system?

Sometimes GA systems have a lot of problems because they are generic as opposed to being designed for and mated to a specific airframe.

For a jet, 180K and 30 deg sounds quite within the normal range, maybe even a bit slow and it should be able to handle that with no problems.

You didn't mention where the "pots" were adjusted. Airframe manufacturer, system manufacturer or your avionics department?

 

[bayoubandit]

Surplus,

Its been awhile since I've flown the RJ, but I believe the avionics are Honeywell. I remember occasionally getting static over the radio also while flying in solid IMC.

From what I know, Cessna Citations (not sure what models) also have the Primus 1000. I think this was the cheapest way, and not really catered towards airlines, but more towards GA.

As far as the pots, I'm not real sure to what your talking about. Was never an avionics wizard, but our avionics department couldn't fix the problem. I'm not sure who adjusted them. It was said that the IC-600 (the brains computer) was slow and that an upgraded computer would be coming in the new planes and I think the others were going to be retrofitted.

From what I remember, the system is Cat II certified. When set up for Cat II, the sensitivity was increased, but I'm not sure how much better it actually was. Our company could not do Cat II, but we could set up for one through the radio alt.

I hope I anwered a few more of your questions. I don't remember alot, its been awhile, maybe Saluki can help out a little more.