B747 Undifferentiated or Other Model
Situational Awareness
ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach; Flight Crew Took Evasive Action
Aircraft; Airport; Weather; Procedure
I was training on the Local Position 1 position. Continuous snow removal operations were in effect; weather was IFR with visibility less than 1 mile; braking action advisories were in effect due to the snow. Runway 7L was in use for arrival.Aircraft X had landed runway 7L and was instructed to exit at taxiway bravo. Aircraft Y was within 1/2 mile of the approach threshold of runway 7L. I attempted to send the aircraft around because I did not believe Aircraft X would be clear of the runway. I was overridden by the On the Job Training (OJTI) at the direction of the Supervisor Controller in Charge (CIC) to let Aircraft Y continue. Aircraft X did not exit the runway by the time Aircraft Y crossed the threshold; the OJTI attempted to send aircraft Y around after the aircraft had already touched down. After that transmission; Aircraft X broadcast that he was stuck and still on the runway.A few minutes earlier I sent a second arrival around due to too close separation in trail on final and preceding aircraft not being able to exit due to runway contamination. Brief facility personnel on definition of 'clear of the runway' as defined in the pilot/controller glossary. Facility front-line management should not emphasize efficiency over safety. Traffic management initiatives should be implemented in an automatic fashion when IFR conditions/runway contamination exists to prevent too close separation on final.
Field conditions at ANC were -SN and a 1/2 mile visibility. Braking action for runway 07L was reported as 5-5-4. 07R was closed for snow removal. The autopilot was engaged and an Initial Operating Experience (IOE) First Officer (FO) was flying. A Flaps 30 landing with autobrakes 3 was chosen for arrival. Prior to touchdown RVR was reported as 4500. The autopilot was disconnected when landing was assured. A normal landing was achieved. The tower asked us to vacate via taxiway C but we were too fast to safely make the turn under the icy conditions. I told the tower that we were unable and would exit at taxiway B. They asked us to expedite as there was another B747 on a 2 mile final behind us. Taxiway B is at a 90 degree angle to the runway. As we approached it; I asked the FO to slow down before taking the turn. As he started to make the left turn; transiting from runway 07R; at about 5-7 knots; the FO reported to me that the aircraft was skidding and that it would not turn any further left and that the brakes were ineffective. I took the controls at that time. I was only able to keep the aircraft on the runway/taxiway using differential power and the aircraft was then slowed to minimum speed. Braking on taxiway B was NIL. I was attempting to stop; but the aircraft continued in an uncontrolled left turn past 90 degrees and was now headed towards the left side of Taxiway B and towards being off the paved surface. I was able to bring the aircraft to a stop before that happened; but the aircraft was precariously close to the edge; and based on my experience; there was a question as to whether the main gear would remain on the paved surface if I attempted a turn back to the right. I informed the tower that we were stuck and that the tail of the aircraft was still on the runway. They told me to clear the runway immediately. I told them I could not. The other B747 was now rolling out as I could see it emerging from the whiteness. I had no choice but to attempt to clear. I applied right tiller and thrust from the number 1 engine and the aircraft nose started to move to the right. I was able to get it back onto taxiway B and onto K. The other 747 was able to clear the runway via taxiway C fortunately and was no longer a factor. Another aircraft was sent around while aircraft Y was still on the runway as well. I reported to ground that there was no braking action on taxiway B. They closed it and sent airport maintenance for inspection. While taxiing on K to parking; a third B747 exited runway 07L in front us. He was cleared to turn left onto taxiway K then right onto R to parking; but they informed ground control that they could not make the 90 degree turn onto K because of the slick surface. Ground control then cleared them continue straight onto G1; further slowing the field surface environment. In the low visibility conditions that prevailed; the spacing of the landing aircraft should have been greater and the B747 that landed behind us; by exactly one minute; should not have been cleared to land until we were positively clear of the runway. When IMC conditions in snow and icing condition are prevalent; and the tower cannot see the landing aircraft well enough due to blowing snow from jet blast or wind; better spacing should be maintained between landing aircraft.
A Tower Controller receiving training described an incident at PANC during snow that required a B747 to go-around twice due to loss of spacing. On the third approach the crew is told to go-around again after they have touched down due to a preceding B747 being unable to completely clear the runway. The Captain elected not to go-around again and the crew was able to stop well before the stuck B747.