TRACON controller described a loss of separation event involving two successive arrival aircraft on ...

Narrative:

I gave a position relief briefing and was completing my overlap when the controller that relieved me cleared a learjet 45 for a visual approach to runway 35 without having the proceeding B737 in sight. The B737 slowed to 130 KTS across the ground and the learjet closed to approximately 3.6 miles behind the B737. Also; the controller switched the learjet late to the tower. The tower had no real opportunity to send the lear around before the B737 crossed the landing threshold. I would have had the lear report the B737 in sight to follow. I asked the lear to report the B737 in sight when I turned the lear base leg. This is the point when the relieving controller assumed responsibility for the position. The lear said he was looking. The relieving controller did not ask the lear a second time to report the B737 in sight. He just asked him to report the airport in sight. When the lear reported the airport in sight the relieving controller cleared him for a visual approach. Later the relieving controller told me that I had a video map and that he was not use to using that 'confused' him as to the end of the runway. We just received a new video map that depicts the final approach courses for the lda and RNAV approaches to runway 35. This map is 'backwards' in it's depiction of the distance markings on final than all of the maps that we have. It makes the runway end appear one mile longer/further south than it really is. The controller thought the B737 was on a mile final when he shipped the lear; when in fact the B737 was on a two mile final instead. This gave the lear more time to catch the B737.

Original NASA ASRS Text

Title: TRACON Controller described a loss of separation event involving two successive arrival aircraft on visual approaches. The reporter listed a new 'video map' that may have been a contributing factor.

Narrative: I gave a position relief briefing and was completing my overlap when the Controller that relieved me cleared a Learjet 45 for a visual approach to Runway 35 without having the proceeding B737 in sight. The B737 slowed to 130 KTS across the ground and the Learjet closed to approximately 3.6 miles behind the B737. Also; the Controller switched the Learjet late to the Tower. The Tower had no real opportunity to send the Lear around before the B737 crossed the landing threshold. I would have had the Lear report the B737 in sight to follow. I asked the Lear to report the B737 in sight when I turned the Lear base leg. This is the point when the relieving Controller assumed responsibility for the position. The Lear said he was looking. The relieving Controller did not ask the Lear a second time to report the B737 in sight. He just asked him to report the airport in sight. When the Lear reported the airport in sight the relieving Controller cleared him for a visual approach. Later the relieving Controller told me that I had a video map and that he was not use to using that 'confused' him as to the end of the runway. We just received a new video map that depicts the final approach courses for the LDA and RNAV approaches to Runway 35. This map is 'backwards' in it's depiction of the distance markings on final than all of the maps that we have. It makes the runway end appear one mile longer/further south than it really is. The Controller thought the B737 was on a mile final when he shipped the Lear; when in fact the B737 was on a two mile final instead. This gave the Lear more time to catch the B737.

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.

Attributes
ACN	1100580
Time
Date	201307
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Visual Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Learjet 45
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Visual Approach
Flight Plan	IFR
Person 1
Function	Departure Approach
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy

TRACON controller described a loss of separation event involving two successive arrival aircraft on visual approaches. The reporter listed a new 'video map' that may have been a contributing factor.