US ATC - Cleared to land

[eeper]

I have operated many times into US airports and have become used to their habit of clearing you to land when there is traffic in front of you and departing. The logic would appear to be that you land at your discretion subject to the runway being clear and this makes sense in good VMC.

However I recently operated into DTW (Detroit Metro) in borderline Cat 1. Cloud was overcast at 100', met vis was 1/4SM and RVR were right on the Cat 1 limits at about 2400'. LVPs were not in force(!). With all this, we were still cleared to land with traffic ahead of us. The only way we had to assess whether the preceding had cleared the runway was observing his TCAS trace reach ground level and then disappear as he presumably turned off his transponder after landing.

Would any US air traffic bods care to comment? At what stage do you stop these "clear to land - number 3" type clearances?

[vector4fun]

Standard procedure in the U.S. Saves us time because we can clear you when we have R/T time and not have to wait/watch and clear you after a preceeding has actually cleared the runway. If spacing and relative speeds look good, just do it. On the other hand, if I think it's going to be tight, I'll always advise the pilot. From the U.S. ATC Handbook, 7110.65:

3-10-6. ANTICIPATING SEPARATION


Landing clearance to succeeding aircraft in a landing sequence need not be withheld if you observe the positions of the aircraft and determine that prescribed runway separation will exist when the aircraft cross the landing threshold. Issue traffic information to the succeeding aircraft if not previously reported and appropriate traffic holding in position or departing prior to their arrival.

EXAMPLE-
"American Two Forty-Five cleared to land, number two following United Boeing Seven-Thirty-Seven two mile final, traffic will depart prior to your arrival."

"American Two Forty-Five cleared to land, number two following United Boeing Seven-Thirty-Seven two mile final, traffic will be an MD 88 holding in position."

Besides, if the aircraft involved are light piston singles or twins, it's quite legal over here to have two or more arrivals on the same runway at the same time...
:eek:

I should have also added, that in low vis ops when I can't see the aircraft exiting the runway, I will, of course always ASK the preceeding aircraft to report clear. You should be able to hear the report as well as I. ASDE radar negates the need for the report natch....

[eeper]

Thanks for the reply vector4fun.

Out of interest, what sort of spacing do you allow if you are making these sequential landing clearances? What sort of allowance do you make for the preceding aircraft missing a turnoff and staying on the runway longer than anticipated? Can I assume that in the tower you are monitoring the vacating aircraft as well as having radar to monitor the position of the next arrival and will issue instructions to go-around if necessary?

The reason I ask is that in the weather conditions we experienced we would have precious few seconds to spot another aircraft on the runway and make the decision for ourselves.

Please note that I am not "getting at" your system, but just trying to understand it so that I can make the "land" decision in confidence. In Europe we are used to receiving a landing clearance only when the runway ahead is clear and "sterile" and in poor weather conditions it takes a load of our mind to know this.

Many thanks.

[Yellow Snow]

You can't rely on pilot reports of vacating. Virtually every pilot report I've seen half the aircraft is still hanging over the runway.
In CAT III LVP conditions how are the pilots going to know they are clear of the LSA?

[Duke of Burgundy]

Yellow Snow - At airports equipped for CAT II/III operations the runway turn-offs normally have colour-coded alternate green and yellow centre-line lights.

An aircraft is clear of the LSA when the whole of the aircraft has passed the end of the colour-coded section and a pilot should delay his runway vacated call until the aircraft has reached that point.

[Captain Spunkfarter]

Yellow Snow

The Duke of Burgundy is correct of course. Haven't you read the AIP?

Then again, don't worry about it. Your landing clearances don't usually take account of stuff still on the runway!

See ya. Wouldn't wanna be ya.

[vector4fun]

Eeper,

At my facility, we have parallels 9,000' and 11,000'. The shorter runway is a Cat III runway. Standard in-trail minimum is three or more miles (wake turbulence) in trail. We have a waiver which allows us to use 2 1/2 miles in trail because we've demonstrated a typical runway occupancy time of less than 50 seconds. See FAA Order 7210.3 :

10-4-7. REDUCED SEPARATION ON FINAL

Separation between aircraft may be reduced to 2.5 NM in-trail separation on the final approach course within 10 NM's of the runway provided an average Runway Occupancy Time (ROT) of
50 seconds or less is documented for each runway. ROT is the length of time required for an arriving aircraft to proceed from over the runway threshold to a point clear of the runway. The average ROT is calculated by using the average of the ROT of no less than 250 arrivals. The
250 arrivals need not be consecutive, but shall contain a representative sample of the types of aircraft that use the runway. Average ROT documentation shall be revalidated, within 30 days, if there is a significant change in runway/taxiway configuration, fleet mix, or other factors that may increase ROT. Revalidation need not be done for situations that are temporary in nature. Only the ROT for the affected runway(s) will need to be revalidated. The revalidation documentation shall contain the following information for each arrival:

a. Aircraft call sign.

b. Aircraft type.

c. Time across the threshold.

d. Time clear of the runway.

e. Items c and d above may be omitted if using a stopwatch. Record the total number of seconds required for an aircraft to proceed from over the landing threshold to a point clear of the runway when using a stopwatch.

Note, however, that we can only use this reduced separation When we can see the aircraft exiting the runway.

When visibility prevents us from seeing the aircraft exit, we normally run our in-trail separation up to about 4 miles, and that typically gives us plenty of "cushion" to get the report clear of runway from the preceeding aircraft.

As for the remarks about aircraft being fully clear, when the weather is low enough that we're below Cat I minima, it's a pretty safe bet that only professionals are still landing, and I trust a Professional Pilot's report that he is in fact, clear. Additionally, we have very good, well lighted high-speed turnoffs with plenty of room between the runway and parallel taxiways, so it's never been a problem here with the pros flying. I am aware there are runway/taxiway configurations which do not allow aircraft to clear so easily and quickly. They wouldn't get the 2 1/2 mile waiver of course....



;)

[Gonzo]

Yellow Snow,

It's going to be interesting when the SMR or whatever it's being called this week (ASMGCSRIMCAS?) goes u/s and we rely on pilots' vacating reports!

Captain Spunky, run out of petrol on the way into work again lately?

Gonzo.

[Captain Spunkfarter]

Gonzo

Nah, but I'll never live it down.

Like yourself, my car was crammed full of juice this morning.

[Yellow Snow]

Duke you are quite correct in what you say about the colour coded lights but I quote.

a pilot should delay his runway vacated call until the aircraft has reached that point.

In my experience these reports are very inaccurate and even worse in VMC runway vacating reports.

Captain you know I've read the AIP you yourself used to phone me up for explanations of terms!

[FWA NATCA]

eeper,

Like someone else mentioned we are allowed to use anticipated seperation. So if the guy that was landing in front of you misses the turn off (and on occasion it happens) you get a go around if I can't get him off before you cross the thresshold.

If the guy that was put in position and then cleared for takeoff doesn't get airborne before you cross the thresshold, LEGALLY I must give you a go around.

But if I'm working the EAA Air Venture air show at OSH (Oshkosh) we work by an entire different set of rules (see the NOTAM) because of the HUGE volume of traffic that we deal with during the show.

Mike