IFR Questions

[rballty]

Are the centerline lights considered as part of the runway enviroment (runway lights?) to which descent can be made to the runway if they are in sight? I always figured they were part of the runway lights, but I saw an interview gouge that implied they were not. I can't find any specifics in the AIM or FAR. Also, is there a good rule of thumb for calculating when and at what rate to climb in order to clear a minimum crossing altitude. Thanks for any information.

 

[PUNISHER]

Yes, CLs (Centerline lights) are considerd part of the runway enviorment. Runway lights, CL or threshold markings/lights, VASI, PAPI, REIL, Red side row or red terminating bar lights are also considered part of the runway enviorment.
Check out the rules of thumbs link, located on the opening page, for your other question.

 

[Pedro]

§ 91.175 Takeoff and landing under IFR.


(a) Instrument approaches to civil airports. Unless otherwise authorized by the Administrator, when an instrument letdown to a civil airport is necessary, each person operating an aircraft, except a military aircraft of the United States, shall use a standard instrument approach procedure prescribed for the airport in part 97 of this chapter.

(b) Authorized DH or MDA. For the purpose of this section, when the approach procedure being used provides for and requires the use of a DH or MDA, the authorized DH or MDA is the highest of the following:

(1) The DH or MDA prescribed by the approach procedure.

(2) The DH or MDA prescribed for the pilot in command.

(3) The DH or MDA for which the aircraft is equipped.

(c) Operation below DH or MDA. Except as provided in paragraph (l) of this section, where a DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, at any airport below the authorized MDA or continue an approach below the authorized DH unless—

(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and for operations conducted under part 121 or part 135 unless that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

(2) The flight visibility is not less than the visibility prescribed in the standard instrument approach being used; and

(3) Except for a Category II or Category III approach where any necessary visual reference requirements are specified by the Administrator, at least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot:

(i) The approach light system, except that the pilot may not descend below 100 feet above the touchdown zone elevation using the approach lights as a reference unless the red terminating bars or the red side row bars are also distinctly visible and identifiable.

(ii) The threshold.

(iii) The threshold markings.

(iv) The threshold lights.

(v) The runway end identifier lights.

(vi) The visual approach slope indicator.

(vii) The touchdown zone or touchdown zone markings.

(viii) The touchdown zone lights.

(ix) The runway or runway markings.

(x) The runway lights.

 

[MauleSkinner]

"runway environment", however, is no longer an approved term...they took it out of the regs so people couldn't use the Golden Arches as their cue to leave minimums.

Fly safe!

David

 

[TIS]

CL lights are NOT - repeat NOT - part of the runway light system.

Yes, CLs (Centerline lights) are considerd part of the runway enviorment. Runway lights, CL or threshold markings/lights, VASI, PAPI, REIL, Red side row or red terminating bar lights are also considered part of the runway enviorment.

They are the centerline lights and that's all. By themselves they are ambiguous at best as they do no provide information about where to land laterally. In other words, if you were to use them by themselves as a landing reference, how would you know whether they were edge lights or centerline lights - in a tight pinch that is? A bad assumption would put you in the weeds or worse.

The definition of the runway edge light system found in the AIM (airport lighting and marking) clarifies what the term "runway lights" as found in 91.175 means. The key here is that nowhere are the centerline lights included in the definition.

You have to dig a little bit to get to the bottom of this and I'm quite sure someone will object to what I'm saying here but I've done the digging. The centerline lights are a stand-alone lighting arragnement.

TIS

 

[Fly_Chick]

Agreed! CL lights are NOT - repeat NOT - part of the runway light system.

You have to dig a little bit to get to the bottom of this and I'm quite sure someone will object to what I'm saying here but I've done the digging. The centerline lights are a stand-alone lighting arragnement.

TIS

I had this question come up on my CFI-I oral. The Pilot Controller Glossary (see Airport Lighting) lists two separate definitions for Runway Lights and Runway Centerline Lights.

b. Runway Lights/Runway Edge Lights- Lights having a prescribed angle of emission used to define the lateral limits of a runway. Runway lights are uniformly spaced at intervals of approximately 200 feet, and the intensity may be controlled or preset.

d. Runway Centerline Lighting- Flush centerline lights spaced at 50-foot intervals beginning 75 feet from the landing threshold and extending to within 75 feet of the opposite end of the runway.

As they are listed as two separate entries, Runway Centerline Lights do not fall into 91.175(c)(x). Of course, common sense should prevail in any approach to a landing.

 

[TIS]

There ya go! That's it!

TIS

 

[Pedro]

I had this question come up on my CFI-I oral. The Pilot Controller Glossary (see Airport Lighting) lists two separate definitions for Runway Lights and Runway Centerline Lights.

b. Runway Lights/Runway Edge Lights- Lights having a prescribed angle of emission used to define the lateral limits of a runway. Runway lights are uniformly spaced at intervals of approximately 200 feet, and the intensity may be controlled or preset.

d. Runway Centerline Lighting- Flush centerline lights spaced at 50-foot intervals beginning 75 feet from the landing threshold and extending to within 75 feet of the opposite end of the runway.

As they are listed as two separate entries, Runway Centerline Lights do not fall into 91.175(c)(x). Of course, common sense should prevail in any approach to a landing.

As usual, Fly_Chick is right!

 

[TIS]

Better look out for the visual approach slope indicator. The abbreviation for that is VASI and that's all that's covered. PAPI doesn't count - for thesame reason that the centerline lights aren't. They're simply NOT in the reg despite the fact that they accomplish the same thing to a higher degree of accuracy.

 

[Fly_Chick]

TIS - were you and I in the same class? Yes, I debated the PAPI as well since it is not included....

Still trying to find the answer on that one.