Go Back  Airline Pilot Central Forums > Career Builder > Technical
What I have always wondered- step down fixes >

What I have always wondered- step down fixes

Notices
Technical Technical aspects of flying

What I have always wondered- step down fixes

Old 10-12-2012, 04:32 PM
  #1  
Gets Weekends Off
Thread Starter
 
Joined APC: Mar 2009
Position: Lunar Lander Commander
Posts: 158
Default What I have always wondered- step down fixes

Lets say you are on an approach with multiple step downs. Lets say you are cleared for the IAP and have 3 step downs to go to MDA. Now lets say you have the runway in sight because the weather is good so you get on the profile and because of this you go below minimum step down altitudes. Is this illegal? 91.175 says that you may descend below MDA/DH when the aircraft is in a position to land using normal maneuvers (3 degree VDP). Does this only apply to MDA/DH or to all minimum altitudes?

Should one always request the visual to CYA? And that is not KCYA if you know what I mean.

Thanks
Denver is offline  
Old 10-12-2012, 04:36 PM
  #2  
Moderator
 
Cubdriver's Avatar
 
Joined APC: May 2006
Position: ATP, CFI etc.
Posts: 6,056
Default

121/135 Op Specs may have a say in this, in other words saying when you can and when you can't go visual on an approach. Are you only interested in Part 91?
Cubdriver is offline  
Old 10-12-2012, 04:55 PM
  #3  
Gets Weekends Off
Thread Starter
 
Joined APC: Mar 2009
Position: Lunar Lander Commander
Posts: 158
Default

In our 135 opspecs their is no mention of this. We are single pilot/autopilot so we have no GOM or FTM so this would apply to all operations I guess. Or it would at least apply to 91 or 135 if not mentioned in opspecs.

Thanks
Denver is offline  
Old 10-12-2012, 05:12 PM
  #4  
Chief Jeppesen Updater
 
FlyerJosh's Avatar
 
Joined APC: Oct 2005
Position: Executive Transport Driver
Posts: 3,080
Default

If you have been cleared for a specific instrument approach, you should comply with the step down altitudes associated with the approach unless otherwise authorized by ATC.

Crews arriving to ORD have been warned/violated for failing to do so. (In most cases the crews intercepted the glideslope and visually descended below the intermediate step downs before the FAF). Because they were not cleared for the visual they dont have much ground to stand on.

Remember, step downs may not just be fore obstacle avoidance. They might also be to avoid other protected airspace for airport underlying the approach. (A good example is the ILS 22L at EWR. The 2500' restriction over GIMEE is for traffic at 1500' departing from TEB.)
FlyerJosh is offline  
Old 10-12-2012, 06:05 PM
  #5  
Gets Weekends Off
Thread Starter
 
Joined APC: Mar 2009
Position: Lunar Lander Commander
Posts: 158
Default

So this would be illegal than. I have a feeling it is even in VMC conditions when you can see the runway. 91.175 just talks about descent below MDA/DH not step down intermediate fix altitudes. So when inside the FAF is one thing but outside is quite another eh?

This is an easy one to screw up in the field.

BTW - This would really only apply to me with approaches like the BC into Santa Maria (KSMX) where it is circling only and the stepdowns are way above 3 degree's. On a normal approach it is not an issue if you are following a normal glide path in most cases.
Denver is offline  
Old 10-12-2012, 06:22 PM
  #6  
Gets Weekends Off
 
galaxy flyer's Avatar
 
Joined APC: May 2010
Position: Baja Vermont
Posts: 5,168
Default

If you are cleared for an instrument approach, you have to fly it, as depicted. Remember the IAP has the force of the FARs, as it is a FAR 97 procedure. If visual and cleared for contact or visual approach, you are OK to maneuver as needed, I see what you mean at KSMX, very steep final due to the antenna. It's similar to the controller, when spacing is getting too close, asking if the have the traffic or the field in sight, you do and he clears you for the visual. The visual eliminates his IFR spacing problem

GF
galaxy flyer is offline  
Old 10-12-2012, 07:14 PM
  #7  
I'm a man of my word.
 
CaptainCarl's Avatar
 
Joined APC: Jul 2008
Position: Devil's Advocate
Posts: 2,883
Default

*always
*then

My job is done here
CaptainCarl is offline  
Old 10-13-2012, 07:59 AM
  #8  
Prime Minister/Moderator
 
rickair7777's Avatar
 
Joined APC: Jan 2006
Position: Engines Turn Or People Swim
Posts: 39,097
Default

Yes you have to unless cleared for the visual. ORD is a perfect example where there might traffic beneath you.

But most airlines do CANPA for non-precision approaches now, and you will clear the vast majority of step downs if you use a 3 degree CANPA, or whatever glide angle is published on the chart. If you're too lazy to do step downs, start practicing CANPA...it works remarkably well. Actually it's safer, so not just a matter of being lazy. It helps to have a GPS to get an accurate groundspeed, but you can use atis winds to make a close estimate.

At SMX nobody is going to care.
rickair7777 is offline  
Old 10-13-2012, 01:35 PM
  #9  
Gets Weekends Off
 
galaxy flyer's Avatar
 
Joined APC: May 2010
Position: Baja Vermont
Posts: 5,168
Default

Kinda hard to fly a CANPA at KSMX. First, it is LOC-based, I not know that you can mix an FMS-derived vertical path with a LOC. Second, it is a V-MDA, not V-RWY (Collins terms)m so the path ends at the FAF. Last, the angle far exceeds 3 degrees, more like 10 degrees for a straight in.

GF
galaxy flyer is offline  
Old 10-13-2012, 02:22 PM
  #10  
Gets Weekends Off
 
USMCFLYR's Avatar
 
Joined APC: Mar 2008
Position: FAA 'Flight Check'
Posts: 13,835
Default

Originally Posted by galaxy flyer View Post
Kinda hard to fly a CANPA at KSMX. First, it is LOC-based, I not know that you can mix an FMS-derived vertical path with a LOC. Second, it is a V-MDA, not V-RWY (Collins terms)m so the path ends at the FAF. Last, the angle far exceeds 3 degrees, more like 10 degrees for a straight in.

GF
You can (meaning that you can build it in the FMS), but that does not give you any obstacle clearance guarantee.

Reposted from the VASI landing thread:
VERY important safety note: Non-precision RNAVs are being published showing a vertical Descent angle (VDA) and TCH on the approach chart. This information can be coded by avionics database providers to provide *advisory guidance* in the final segment. However, there is no TERPs criteria for obstacle clearance for the VISUAL segment of the path below the MDA. Consequetnly, if the VDA is blindly followed below MDA, an aircraft may come too close to, or impact obstacles or terrain penetrating the 34:1 surface extending out from the runway....
It is the pilot's responsibility to use the barometric altimeter to ensure compliance with altitude restrictions. Advisory vertical guidance is not approaved vertical guidance like that found on approaches with L/VNAV, LPV, ILS lines of minima. Advisory vertical guidance does not provide a TERPS-protected glidepath.

In short - BE CAREFUL!
USMCFLYR

Last edited by USMCFLYR; 10-13-2012 at 02:34 PM.
USMCFLYR is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
CitationJason
Regional
61
11-22-2019 05:53 PM
Pilot_135
Career Questions
16
05-22-2011 02:13 PM
Longbow64
Flight Schools and Training
9
03-09-2011 05:01 PM
gintasr
Regional
586
07-02-2008 12:31 PM
brownie
Regional
12
02-11-2008 07:36 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Thread Tools
Search this Thread
Your Privacy Choices