Narrative:

A MD88 was on final approach to runway xxr; about a 12 NM final. We were notified that an MD80 was returning to the airport with smoke in the cockpit; he had just departed the airport about 2 minutes prior. I pulled his tag up and he was about 5 NM west of the airport on a modified downwind to runway xxr. The final controller called and told me to put the MD88 on runway xxl that the MD80 was going to runway xxr. I cleared the MD88 for a visual approach to runway xxl and also cleared him to land. There was a military exercise going on in the uncontrolled area between runway yy and runway xxl. This exercise required several crash fire rescue equipment vehicles to be attendant to the exercise for fire safety during the operations. When I got word about the emergency aircraft; I called the fire truck and told him about the emergency. The fire truck was also at the military ramp and requested to transition to the west side of the airport where the emergency MD80 would be landing. I told the fire truck to cross runway yy and runway xxl. About ten seconds later I noticed the MD88 flaring out over the numbers on runway xxl. The fire truck had just crossed runway yy and was about 500 ft from the intersection of taxiway C and runway xxl when the MD88 crossed the same intersection. I reiterated for the fire truck to cross runway xxl and contact ground control (ground control) on the other side. Although the timing was such that the fire truck could not have made it to the intersection to be a factor for the MD88; it still startled me and I realized that there was a potential for a serious runway incursion. Added to this scenario were two runway yy arrivals; frequency confusion with crash fire rescue equipment command; and the emergency MD80. This plus the fact that two crash fire rescue equipment vehicles were in a different place than usual contributed to the work load. I should have kept my arrival pad up to date and noted the fact that the MD88 was now going to runway xxl and not runway xxr. This would have been a visual clue that runway occupancy would have prevented me from crossing the fire truck. I also used incorrect phraseology/procedures in issuing two crossing clearances in one transmission to the fire truck. Adherence to proper phraseology would have given me a second opportunity to ensure runway separation.

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Original NASA ASRS Text

Title: Tower Controller described an unsafe event involving runway crossings; several Emergency vehicles participating in a military exercise; and other Emergency vehicle responding to an inbound emergency Air Carrier aircraft.

Narrative: A MD88 was on final approach to Runway XXR; about a 12 NM final. We were notified that an MD80 was returning to the airport with smoke in the cockpit; he had just departed the airport about 2 minutes prior. I pulled his tag up and he was about 5 NM west of the airport on a modified downwind to Runway XXR. The Final Controller called and told me to put the MD88 on Runway XXL that the MD80 was going to Runway XXR. I cleared the MD88 for a Visual Approach to Runway XXL and also cleared him to land. There was a military exercise going on in the uncontrolled area between Runway YY and Runway XXL. This exercise required several CFR vehicles to be attendant to the exercise for fire safety during the operations. When I got word about the emergency aircraft; I called the fire truck and told him about the emergency. The fire truck was also at the military ramp and requested to transition to the west side of the airport where the emergency MD80 would be landing. I told the fire truck to cross Runway YY and Runway XXL. About ten seconds later I noticed the MD88 flaring out over the numbers on Runway XXL. The fire truck had just crossed Runway YY and was about 500 FT from the intersection of Taxiway C and Runway XXL when the MD88 crossed the same intersection. I reiterated for the fire truck to cross Runway XXL and contact Ground Control (GC) on the other side. Although the timing was such that the fire truck could not have made it to the intersection to be a factor for the MD88; it still startled me and I realized that there was a potential for a serious runway incursion. Added to this scenario were two Runway YY arrivals; frequency confusion with CFR command; and the emergency MD80. This plus the fact that two CFR vehicles were in a different place than usual contributed to the work load. I should have kept my arrival pad up to date and noted the fact that the MD88 was now going to Runway XXL and not Runway XXR. This would have been a visual clue that runway occupancy would have prevented me from crossing the fire truck. I also used incorrect phraseology/procedures in issuing two crossing clearances in one transmission to the fire truck. Adherence to proper phraseology would have given me a second opportunity to ensure runway separation.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.