Air Traffic Controller Discussion With a Global Perspective
By Dhruv Kalra 878508
#529476
Simon Kelsey 810049 wrote:I'm not sure what the FAA rules are regarding takeoff minima as I can't find a reference in the AIM and I don't know my around the FARs but presumably there must be some sort of visual reference requirement?

“Adequate visual reference” is defined in FAA takeoff minima as an alternative to or as a supplement to RVR values.

Either way, that’s besides the point. You don’t need to taxi the length of a displaced threshold to read painted runway numbers in order to count lights. That’s the original question.
By Alex Seeberger 1129791
#529482
Simon Kelsey 810049 wrote:
Alex Seeberger 1129791 wrote:Regardless of the required visibility to initiate or continue an approach, at minimums the pilot must be reasonable sure the visibility is within limits, in their opinion to continue to landing. How many runway lights are required if the minimums are 550 meters? Can you reliably count that at 150 knots during a night approach:)


You're comparing apples and oranges.

The visual references required at DH on approach are, of course, very different to those required for an LVTO and clearly defined (at least in EASA land -- I assume also in the AIM). For a CAT I approach, that would basically be 'something' (at least one of the runway, runway threshold markings, runway edge lights, elements of the approach lighting system, PAPIs, touchdown zone markings/lights etc). For CAT II, at least three consecutive lights including a lateral element are required, CAT IIIA requires three lights, IIIB with a DH requires one light, and IIIB no DH no visual references at all are required before touchdown. I believe the USA is similar in this regard.


Sorry man...I meant for the post to be tongue-in-cheek. The point was more of an operational rather then regulatory philosophy. The point was:

In the US

1) We use the entire usable takeoff runway available, regardless of visibility.

2) Most operators don’t emphasize counting runway lights when determining takeoff visibility requirements (non-regulatory) .
By Andreas Fuchs 810809
#529493 A runway can be identified by means of a localizer and we do that in LVP. But how else would you ensure that you have a visual segment of 90 metres or more, except for counting lights? Counting lights is the most reliable method, but you will most likely need this only with RVRs below approx. 200 metres. On the other hand I am sure that at JFK not even European operators will taxi forward thousands of feet to the displaced threshold. How often does JFK operate with an RVR of less than 200 metres? Do you have RCLs with a spacing of 15 metres right from the beginning of the runway and not only from the displaced threshold?
Last edited by Andreas Fuchs 810809 on Thu Dec 20, 2018 10:45 am, edited 1 time in total.
By Rob Nabieszko 1138610
#529532
Dhruv Kalra 878508 wrote:
Rob Nabieszko 1138610 wrote:While RVR is a useful information tool, it is not located on the runway, where the visibility matters. Although unlikely, there could be variations from the runway to where the RVR equipment is located.


I’m sorry, but what? RVR, the equipment that measures Runway Visual Range, isn’t located on the runway? Unless you’re referring to a scenario where you’d be on a non-RVR Runway at an airport where not all runways have RVR equipment, that statement is categorically incorrect.

https://en.wikipedia.org/wiki/Runway_visual_range


It is important to understand exactly how RVR is designed to be able to apply the information it provides in a useful manner. A sensor measures the incoming light from a light located a fixed distance away, and translates this to a distance the pilot should be able to see. But like any other instrument, that value is only valid for the immediate area being measured.

It is truly important to consider WHERE the RVR sensor is mounted, relative to our departure runway.

Laterally: They are not located on the runway. Not even close. The FAA requires them to be mounted (at least) 400 feet laterally away from the runway centreline. I was unable to find a TC/ICAO/EASA reference, but from personal observation, they are several hundred feet from the centreline. (The sensor is normally 14 feet tall - you wouldn't want it too close to the runway.)

Longitudinally: Threshold and rollout installations in the US (again, the only docs a cursory google search revealed) are required to be installed within 2500 feet of each runway threshold. If you are departing from one of the displaced thresholds that started this whole thread, add the threshold displacement to that 2500. You could be a half mile or more from the RVR sensor.

The point is that the only truly accurate measurement of the visibility on the runway is the pilot looking at the runway.

Don't get me wrong, RVR is a fantastic tool. It gives us a great idea of what to expect when we get to the runway, whether it is even worth leaving the gate. But I have seen several occasions in my career where the RVR values across an airport have been completely different. 800 at one end, and 6000 at the other. The RVR value should always be taken with a grain of salt, and not regarded as gospel truth.

And counting runway lights in Canada during RVOP/LVOP is the standard all pilots operate by, or at least what is expected of all the operators I have dealt with.

Would you cross a runway without looking left and right, just because the controller cleared you to? Would you cross a street just because the light turned green? Are you willing to bet your life that every car will stop at the red light? Just another layer of increasing safety.

Rob
By Andreas Fuchs 810809
#529536 Hi Rob,

thanks, great post. I tried to explain this with my example from Moscow Vnukovo, but somehow nobody read or believed it.

Jeppesen charts actually show the position of RVR measuring equipment at many airports. Funnily, charts in the US do not seem to have this piece of information (I checked JFK and ORD).

The screenshot shows EDDF/Frankfurt airport, I have circled the RVR measuring equipment. As you can see, it can be quite far from the centerline.
Image
By Matt Bromback 816206
#529539
Rob Nabieszko 1138610 wrote:
Dhruv Kalra 878508 wrote:
Rob Nabieszko 1138610 wrote:While RVR is a useful information tool, it is not located on the runway, where the visibility matters. Although unlikely, there could be variations from the runway to where the RVR equipment is located.


I’m sorry, but what? RVR, the equipment that measures Runway Visual Range, isn’t located on the runway? Unless you’re referring to a scenario where you’d be on a non-RVR Runway at an airport where not all runways have RVR equipment, that statement is categorically incorrect.

https://en.wikipedia.org/wiki/Runway_visual_range


It is important to understand exactly how RVR is designed to be able to apply the information it provides in a useful manner. A sensor measures the incoming light from a light located a fixed distance away, and translates this to a distance the pilot should be able to see. But like any other instrument, that value is only valid for the immediate area being measured.

It is truly important to consider WHERE the RVR sensor is mounted, relative to our departure runway.

Laterally: They are not located on the runway. Not even close. The FAA requires them to be mounted (at least) 400 feet laterally away from the runway centreline. I was unable to find a TC/ICAO/EASA reference, but from personal observation, they are several hundred feet from the centreline. (The sensor is normally 14 feet tall - you wouldn't want it too close to the runway.)

Longitudinally: Threshold and rollout installations in the US (again, the only docs a cursory google search revealed) are required to be installed within 2500 feet of each runway threshold. If you are departing from one of the displaced thresholds that started this whole thread, add the threshold displacement to that 2500. You could be a half mile or more from the RVR sensor.

The point is that the only truly accurate measurement of the visibility on the runway is the pilot looking at the runway.

Don't get me wrong, RVR is a fantastic tool. It gives us a great idea of what to expect when we get to the runway, whether it is even worth leaving the gate. But I have seen several occasions in my career where the RVR values across an airport have been completely different. 800 at one end, and 6000 at the other. The RVR value should always be taken with a grain of salt, and not regarded as gospel truth.

And counting runway lights in Canada during RVOP/LVOP is the standard all pilots operate by, or at least what is expected of all the operators I have dealt with.

Would you cross a runway without looking left and right, just because the controller cleared you to? Would you cross a street just because the light turned green? Are you willing to bet your life that every car will stop at the red light? Just another layer of increasing safety.

Rob


You make some very bizarre statements when it comes to RVR such as "pilot looking down the runway" As a pilot there is literally no way to tell what the RVR is....We rely on the equipment on providing guidance, company procedures, OPS Specs, aircraft capability, and runway equipment to determine whether or not the takeoff is legal.

I just want to make sure people don't misunderstand what your saying. It is a very systematic approach (airlines) take to whether or not it is safe to land or takeoff in low visibility situations.
By Andreas Fuchs 810809
#529541 Hi Matt,

please read through the last few posts, where it was pointed out how and why pilots HAVE TO determine a visual segment. I am disappointed to read messages like yours. Why are us real commercial pilots posting here at all? It seems to be useless and unwelcome.
By Matt Bromback 816206
#529544
Andreas Fuchs 810809 wrote:Hi Matt,

please read through the last few posts, where it was pointed out how and why pilots HAVE TO determine a visual segment. I am disappointed to read messages like yours. Why are us real commercial pilots posting here at all? It seems to be useless and unwelcome.


Since I am unwelcome here let me respond

I don't really care where you fly, or how you fly. What I am merely pointing out is the way you have been describing it is not the golden standard.

Example I can depart with RVR 5/5/5 and ALL have to be controlling, the only requirement is that the HIRL and CL are operational, RCLM are not required so I don't have to see anything visually, just the lights (and no I for sure don't count them). The runway either has the appropriate lights installed for low visibility takeoffs or not, its simple as that. The 737 is authorized to takeoff even lower down to RVR 300 because of the HUD. Comparing US airports to EU airports the Jepp charts (10-9A) have the information displayed the exact same way, only difference is Meters.

You might be quoting EASA regulations and whatever else you can find, but you have to remember companies can get authorization from the government to conduct certain low visibility operations that differ from the regs. In the US we call them OPS specs I assume there called the same thing internationally, maybe not, but I guarantee British Airways follows the same techniques as American, or Qantas, or Emirates.
By Andreas Fuchs 810809
#529545
I don't really care where you fly, or how you fly. What I am merely pointing out is the way you have been describing it is not the golden standard.
??? Seriously? How often do we have to write that we get bloody FAILED in the SIM, if we don't do this? That's not exclusive to Europe.
By Dhruv Kalra 878508
#529546
Andreas Fuchs 810809 wrote:
I don't really care where you fly, or how you fly. What I am merely pointing out is the way you have been describing it is not the golden standard.
??? Seriously? How often do we have to write that we get bloody FAILED in the SIM, if we don't do this? That's not exclusive to Europe.

Only thing we got failed in the sim on during 500ft RVR takeoffs was if we failed to verify that all required controlling RVRs and lighting were available. Nothing about counting lights.
By Rob Nabieszko 1138610
#529554 Ok.

I think we all need to dial it back a bit (myself included).

The only point I orignally wanted to make was that RVR was not to be taken as infallible or a perfect representation of runway visibility. Pilots should and must remember to exercise good judgement and not take any action based solely on a single aource of information.

I will also gladly concede that different jurisdictions have varying training and procedure standards. I took issue with the statement that "No one counts lights, except the keeners." Some of us do, because some of us are required to.

I enjoy this community because it is a global community. I am privileged to learn how we differ, as we all enjoy the common elements we all share. I regret this post devolved into a bit of a war. I was glad to learn something.

Rob
By Mike Lehkamp 1396931
#531462
Andreas Fuchs 810809 wrote:Hi Rob,

Simon already gave you the answer that is valid in 99% of cases. I would like to add that during low visibility conditions/operations pilots are to identify the runway by seeing its markings (numbers). For doing so, it will be necessary to slowly taxi forward to the displaced threshold and then wait there, when you can read the runway identifier.


BINGO! Thank you Andreas.

Mike