CRJ Critical AOA

[BeechDawg]

I guess if they are asking questions like that at the interview then they will find themselves with classes full of All ATPs and Regional Airline Academy students. Maybe some from Riddle as well. Which I thought was exactly what they were trying to get away from with Gulfstream.

If I was asked that for the ERJ, I'd say, "When the pitch limit indicator says so."

They definately don't teach you that at All ATPS, they don't teach you anything.

 

[FlyChicaga]

http://www.atpflightschool.com/programs/certificates/crj/crj_orientation.html

No?

 

[FR8mastr]

Unless your AC has a AOA indicator what diff does it make? does the CRJ have one?

 

[BeechDawg]

http://www.atpflightschool.com/programs/certificates/crj/crj_orientation.html

No?

Have you taking any ratings through ATPs, maybe they're pass rate needed a boost so they add a program that you can't fail. Just invest Thousands of dollars into a program that won't even get you a job instructing with them. BTW when I went through this was not available.

 

[ekuflyer]

No the crj does not have an AOA indicator, so who knows what the critical angle is. Most a/c that do use some random AOA units anyway so you still wouldn't know the true angle.

 

[BeechDawg]

The following quote is from one of our instructors here at SkyWest:



"GREEN LINE- is displayed on the PFD airspeed scale as an indication of approximately 1.265 Vs for the Flap configuration. It can be considered as a bracket that extends from the top of the slow speed checkerboard to 1.265 of stall speed. It reacts in the same way as the shaker boundary and can be viewed as an extension of it (not approved by the FAA as a sole means to fly an approach).



• Green line is subject to certain errors, which must clearly be understood before we can properly interpret it:



 The position of green line is calculated according to information from the stall protection computer, which can only compute the pusher-firing angle for the present Mach number. This means that green line can never be more accurate than (+/-) 2 to 3 knots. Furthermore, the greater the difference between the present Mach number and the stalling Mach number, the more green line will be in error on the high side. The closer that we fly to Vref for the flap setting, the more accurate green line becomes.



 The stall computer and Green line have different settings for each flap configuration. During flap extension or retraction, green line is momentarily unusable. We cannot rely on green line if the flaps have failed in any position other than the approved flap settings.



• The margins that we recommend for maneuvering and final approach allow for the increase in stalling speed as bank and/or G increases. This can be seen as the green line climbs to some higher value. Remember that as long as you are at green line or above, you have sufficient margin for 30 degrees of bank. During turbulence at speeds close to Vref, green line movement is relative to the angle of attack and could be used as a further confirmation of gust margins during approach. It is safe to say that if you are below green line in stabilized 1-G flight, you are below Vref for the flap setting.



Simply said, the green line at FL350-cruise flt-m.74 is not accurate because the aircraft is futher away from the stalling mach number. Example: Next time your in the sim, have the insructor "slew" you to 35000 feet and "slew" speed to 262kt(m.77). The green line will appear at a speed of approximety 230kts indicated. Do you really think the stall speed is that high at this altitude. Of coures not. Now, with the auto-pilot on, reduce the thrust to flight-idle. Which direction will the green line move (up, down or stay the same)? It will slowly move down as airspeed decreases. However, as the explanation stated, the aircrafts mach speed is decreasing therefore the green line is becoming more accurate as the aircraft decelerates. As the the aircraft approaches approximately 200kts indicated, the green slows to almost a complete stop and airspeed of the aircraft falls below the green line. Up to this point, we have NEVER fallen below this reference indicator until now. Now guess what you're going to see? That's right the LOW SPEED CUE (red barber pole). Now you're close to the stall. Again, keep in mind this was done in a 1g maneuver. Now,at the same conditions as previously mentioned, kick the auto-pilot off and perform a 45 degree back turn, and watch the green rise to a higher value than where it originally started. This is because in a banked maneuver, the stall speed has now increased by virtue of increased load factor. In this example, the difference between the present MACH number and the STALLING MACH number was reduced by the increase in bank therefore making the green line MORE accurate.

Now, if you're flying around, 370, 390, 410, and in a 1g straight and level cruise flight (m.74), you may see the slow speed cue and the high speed cue within the range of the air speed indicator. We all know that this is known as "coffin corner". The very small operating area of flight. Even though we are at cruise m.74, this mach number is much closer to the stalling mach number than it was previously at FL350. Therefore, once again making the green line more accurate in this example."

Maybe this is good enough for them

 

[91100 100 set]

Knowing this kind of thing might be interesting just from a trivia point of view for airplane buffs. Personally, I think it would be interesting for just that reason. But for actually operating the airplane, unless there is some way to showing this information in some usable format to the pilot (say, flying an approach at a given AoA or for setting up a given cruise configuration), who cares?

If they ask in an interview, just say "13 degress" with a straight face. Thats probably close enough. And then wonder if the HR person asking you this even knows what she is asking you. Or ask the asst chief pilot sitting next to her if they mean local airflow on a given airfoil section or total airflow, and watch his face.

 

[N813CA]

This is what you need to know about the CRJ. Well done.

Originally Posted by SkyWestCRJPilot
The following quote is from one of our instructors here at SkyWest:



"GREEN LINE- is displayed on the PFD airspeed scale as an indication of approximately 1.265 Vs for the Flap configuration. It can be considered as a bracket that extends from the top of the slow speed checkerboard to 1.265 of stall speed. It reacts in the same way as the shaker boundary and can be viewed as an extension of it (not approved by the FAA as a sole means to fly an approach).



• Green line is subject to certain errors, which must clearly be understood before we can properly interpret it:



 The position of green line is calculated according to information from the stall protection computer, which can only compute the pusher-firing angle for the present Mach number. This means that green line can never be more accurate than (+/-) 2 to 3 knots. Furthermore, the greater the difference between the present Mach number and the stalling Mach number, the more green line will be in error on the high side. The closer that we fly to Vref for the flap setting, the more accurate green line becomes.



 The stall computer and Green line have different settings for each flap configuration. During flap extension or retraction, green line is momentarily unusable. We cannot rely on green line if the flaps have failed in any position other than the approved flap settings.



• The margins that we recommend for maneuvering and final approach allow for the increase in stalling speed as bank and/or G increases. This can be seen as the green line climbs to some higher value. Remember that as long as you are at green line or above, you have sufficient margin for 30 degrees of bank. During turbulence at speeds close to Vref, green line movement is relative to the angle of attack and could be used as a further confirmation of gust margins during approach. It is safe to say that if you are below green line in stabilized 1-G flight, you are below Vref for the flap setting.



Simply said, the green line at FL350-cruise flt-m.74 is not accurate because the aircraft is futher away from the stalling mach number. Example: Next time your in the sim, have the insructor "slew" you to 35000 feet and "slew" speed to 262kt(m.77). The green line will appear at a speed of approximety 230kts indicated. Do you really think the stall speed is that high at this altitude. Of coures not. Now, with the auto-pilot on, reduce the thrust to flight-idle. Which direction will the green line move (up, down or stay the same)? It will slowly move down as airspeed decreases. However, as the explanation stated, the aircrafts mach speed is decreasing therefore the green line is becoming more accurate as the aircraft decelerates. As the the aircraft approaches approximately 200kts indicated, the green slows to almost a complete stop and airspeed of the aircraft falls below the green line. Up to this point, we have NEVER fallen below this reference indicator until now. Now guess what you're going to see? That's right the LOW SPEED CUE (red barber pole). Now you're close to the stall. Again, keep in mind this was done in a 1g maneuver. Now,at the same conditions as previously mentioned, kick the auto-pilot off and perform a 45 degree back turn, and watch the green rise to a higher value than where it originally started. This is because in a banked maneuver, the stall speed has now increased by virtue of increased load factor. In this example, the difference between the present MACH number and the STALLING MACH number was reduced by the increase in bank therefore making the green line MORE accurate.

Now, if you're flying around, 370, 390, 410, and in a 1g straight and level cruise flight (m.74), you may see the slow speed cue and the high speed cue within the range of the air speed indicator. We all know that this is known as "coffin corner". The very small operating area of flight. Even though we are at cruise m.74, this mach number is much closer to the stalling mach number than it was previously at FL350. Therefore, once again making the green line more accurate in this example."

 

[FL000]

For a while there, I thought I was cruising airliners.net!

 

[bitememesa]

Yes because everyone knows that coffin corner is caused by the critical angle of attack (ehhh! WRONG!) and it's sooooooo tight on the CRJ...especially if they're a Riddle grad like some of us may be (you got a problem champ?). God I was in coffin corner the other day and just about pissed myself when I realized it was like 50 knots wide and that if I went too slow, my wing would be unable to maintain laminar flow and if I went to fast, the shockwave moving along the wing and horizontal stabilizer would render my controls useless

Everyone be afraid...the CRJ can stall and do unpredictable things if you're retarded. Keep your winner-like Skywest crap off of here. It still doesn't answer the original question, what is the critical AoA of the CRJ, which is probably upwards of 25 degrees due to the high sweep and critical nature of the wing. If that's not good enough for Pinnacle...well then I still don't think it will help anything.

 

[PCL_128]

If idiotic interview question like this don't convince you that PCL is NOT the place you want to work, then there's nothing I can do to help you. Trust me, run far, far away from Pinch-nickle.

 

[FlyHigher]

Still no answers!!

Ok, for those of you that suggest to give a "smart answer" THIS IS A WRITTEN TEST!!!! So, no way to talk yourself out of it. In the interest of passing that interview, maybe some of the Academy graduates can actually help their fellow pilots. I thought this forum is to help each other out and to network.
Here some other questions that we have to find the answer to:

1) Critical angle of attack: so the consenses here is 10 degrees?????
2) Recovery from a 130 degree windshear upset?
3) What is an RTU and an inverter?
4) Difference between PDP and VDP?
5) Cleared for the VISUAL approach and frequency is congested, what do you do? Fly puplished missed, pattern, or RWY heading?
6) Min/max G loads on transport category a/c?
7) Why is it harder to recover from a stall at high altitude (vs. low altitude)?
8) M l/d in jets gives you what?
9) What heats (not cools) engine oil?
10) What is most severe, rime, clear ice, or freezing rain?
11) Define coffin corner
12) Define deck angle

Any takers???

 

[Kaman]

I think you meant TRU (Transformer Rectifier Unit)

 

[PCL_128]

I think you meant TRU (Transformer Rectifier Unit)

Well, it could be either.

RTU=Radio Tuning Unit
TRU=Transformer Rectifier Unit

RTUs are the units in the CRJ that are used to tune the COMMs, NAVs, ADFs, etc... TRUs convert AC power to DC. Inverters convert DC power to AC.

 

[Mkay?]

Disclaimer: I am trying to help. If I am wrong then go easy on me .... My PC is not for another month or two, so I still have time to cram!!

1. This is how I would answer this question: The critical angle of attack for the CRJ is the highest angle of attack at which air passes over the airfoil in a smooth (or laminar for you nerds) flow. I think putting a number value (i.e. 10 degrees) is a waste of time as it is not a measureable value from the cockpit. Also as an aside, I would be careful citing the "green line" in your discussion. It is my understanding that SkyWest wanted this option on the PFD and that is was a carryover item from certification. Are there other CRJ operators out there that have a green line on the speed tape?

2. I think that this question needs more explanation. But if I assume that you have rolled 130 degrees then this would be my answer. The common stratgey on upsets in transport category aircraft is to first roll wings level, then adjust pitch as necessary.

3. A TRU is a transformer rectifier unit. It is used to convert AC power to DC power. An inverter is used to convert DC power to AC.

4. A PDP is a Planned Descent Point. It is a point on an approach where a pilot would start a normal decent to landing. (Usually a 3 degree glide path) There are various equations to create a PDP, and everyone has their favorite. A VDP or Visual Descent Point is a point on an approach where the normal descent to a landing must occur at or after. The main difference between the two is that the PDP is created by the pilot and non regulatory, whereas the VDP is created by the TERPS (represented by a V on Jepp charts) and is regulatory.

5. This is a question mainly designed to see how you think. I think the best answer is that since you are on an IFR flight plan and cleared for an IFR approach, you would fly the published missed approach. The published missed is desinged to keep you out of the way and I can't see you flying a nice rectangle pattern at O'Hare.

**CENSORED****CENSORED****CENSORED****CENSORED** ... gotta go. Maybe someone else will help with the rest. I'll try to get them later if I can.

 

[Kaman]

Hello,
Oh OK...learn something new everyday. We called those CDUs (Control Display Units) in the helicopter I flew in. Got to love all these bloody acronyms! Aviation has WAY too many...

Regards,

ex-Navy Rotorhead

 

[PCL_128]

Hello,
Oh OK...learn something new everyday. We called those CDUs (Control Display Units) in the helicopter I flew in. Got to love all these bloody acronyms! Aviation has WAY too many...

Regards,

ex-Navy Rotorhead

Oh, we've got those too. The FMS head is called an MCDU for Multifuntion Control Display Unit. Don't you just love aviation terminology.

 

[Rez O. Lewshun]

5. This is a question mainly designed to see how you think. I think the best answer is that since you are on an IFR flight plan and cleared for an IFR approach, you would fly the published missed approach. The published missed is desinged to keep you out of the way and I can't see you flying a nice rectangle pattern at O'Hare.

Designed to keep you out of the way? I'd love to see me doing a nice VFR pattern at ORD, JFK, EWR, LGA, DCA etc......

Do a MAP in LGA ILS 22 ( http://204.108.4.16/d-tpp/0504/00289I22.PDF ) and the flight path will jam up northbound Korry3 arrivals ( http://204.108.4.16/d-tpp/0504/00289KORRY.PDF ) In fact, the ILS 22 MAP hold fix is PROUD intersection, which is the last fix on the Korry3 arrival.

A MAP for JFK ILS 31R sends the aircraft to Canarsie and Colts Neck. Too close to EWR and thier departure procedures (for me). http://204.108.4.16/d-tpp/0504/00610I31R.PDF

The approach briefing goes like this.... "it'll be a visual app backed up by the ILS .......blah blah blah..... in case of a Go Around we'll fly the published MAP." Huh? WTFO?

The reason we default to published MAP is the training world. The FAA PTS and company training programs require pilots to demonstrate the ability to execute a MAP. However, Flying the Line is not a PTS checkride......

It is very fustrating to see professional pilots plan for and accept a visual approach clearance with a full published instrument MAP primed and ready to go in the back of thier minds... from the Dogs....

The Visual Approach Go-Around​

By Capt. Brad Alberts​

​

Ask any group of pilots what the proper procedure is for the go-around from a visual approach, and you are bound to get a variety of answers. Throw in a communication problem (busy/block/lost frequency/ actual NORDO on the go) and the answers become even more interesting and less obvious. Aside from the great number of risks that crew takes by accepting a visual approach in the first place, there is a need to determine the proper course of action for a go-around off a visual approach clearance.​

This issue was taken up at Air Traffic Procedures Advisory Committee (ATPAC) in July 2000. FPA is a voting member of this FAA advisory committee. After much discussion and a review of a number of documents, it was determined that sufficient guidance exists and no further changes to FAA publications would be required.​

Here is what we found. First, pilots are expected to remain VMC. The published Missed Approach Procedure (MAP) is not available on a visual go-around. So don’t use it. What does ATC expect you to do? If you have operating radios (99.999 percent of the time) the tower will give you instructions—probably to turn, or to climb, or both. An aircraft going around becomes their top priority. You’ll be re-sequenced with existing traffic and given another approach.​

What if you cannot contact the tower? It’s rare, but it does happen. You’re still required to remain VMC. At this point, you’re treated like a NORDO VFR aircraft in the traffic pattern. ATC will take the appropriate action clearing traffic for you. Of course, you’re going to make every attempt to contact the tower (try guard frequency?). You are expected to turn crosswind (left or right traffic, appropriate to the circumstances and the runway configuration), downwind, base, and final in accordance with standard AIM procedures. (Do you remember tower light gun procedures?) Also, the pilot/controller glossary has information under Go-Around.​

Your FPA Safety Committee recommends that unless conditions are picture-perfect and the airport, runway, and traffic to be followed are rock-solid, accepting a visual approach clearance is highly questionable. The ILS or other IFR approach procedure is always preferable. Fly safely.​

There is more!

This is from the ATC Controller handbook. Reading it will take you to the next level.

http://www.faa.gov/ATpubs/ATC/Chp7/atc0704.html#7-4-1

7-4-1. VISUAL APPROACH​

A visual approach is an ATC authorization for an aircraft on an IFR flight plan to proceed visually to the airport of intended landing; it is not an instrument approach procedure. Also, there is no missed approach segment. An aircraft unable to complete a visual approach shall be handled as any go-around and appropriate separation must be provided.​

[size=-2]REFERENCE-​

FAAO 7110.65, Wake Turbulence Cautionary Advisories, Para 2-1-20.
FAAO 7110.65, Forwarding Approach Information by Nonapproach Control Facilities, Para 3-10-2.
FAAO 7110.65, Visual Separation, Para 7-2-1.
FAAO 7110.65, Approaches to Multiple Runways, Para 7-4-4.



The AIM. Sometimes it needs to be dusted.

http://www.faa.gov/ATpubs/PCG/G.HTM​

GO AROUND- Instructions for a pilot to abandon his/her approach to landing. Additional instructions may follow. Unless otherwise advised by ATC, a VFR aircraft or an aircraft conducting visual approach should overfly the runway while climbing to traffic pattern altitude and enter the traffic pattern via the crosswind leg. A pilot on an IFR flight plan making an instrument approach should execute the published missed approach procedure or proceed as instructed by ATC; e.g., "Go around" (additional instructions if required).​

MISSED APPROACH-

a. A maneuver conducted by a pilot when an instrument approach cannot be completed to a landing. The route of flight and altitude are shown on instrument approach procedure charts. A pilot executing a missed approach prior to the Missed Approach Point (MAP) must continue along the final approach to the MAP.










b. A term used by the pilot to inform ATC that he/she is executing the missed approach.

c. At locations where ATC radar service is provided, the pilot should conform to radar vectors when provided by ATC in lieu of the published missed approach procedure.










​

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[rptrain]

bitememesa and Rez have restored my faith in humanity.

 

[PCL_128]

Glad to have you here at PCL Rez. It's nice to have someone around that knows what they're doing. 90% of our pilots would answer the question incorrectly and do the published missed.

"This will be a visual backed up by the ILS..... If we have to go missed we'll follow tower's instructions or do the published missed." If I had a dollar for every time I heard that BS...