While on the river visual to runway 19 at dca; a B737-700 captain is instructed to square his turn t...

Narrative:

We were cleared for the river visual to runway 19 after sequence vectors off the frdmm 3 arrival. We intercepted the river north of the georgetown reservoir and checked in with dca tower. We were given 'cleared to land 19.' followed shortly by 'slow to final approach speed.' we complied while following the river. As we approached the key bridge; tower requested we 'square the corner to final.' we quickly confirmed that we could not come left in order to square the corner due to area P-56. We continued our ground track so as to [not] violate P-56. We had no conflict with departing traffic and had an uneventful landing.in a pilot's mind; 'square the corner to final' means turn to 90 degrees off final; then make one 90 degree turn to line up on final. In this case; when given the request by tower (and without superior situational awareness) we could have turned directly into P-56. I recommend that tower use 'square the turn to final' only on runway 1. Also; list a warning on company dca safety alert page detailing this possibility by the tower.

Original NASA ASRS Text

Title: While on the River Visual to Runway 19 at DCA; a B737-700 Captain is instructed to square his turn to final for spacing by the Tower. He declines due to the presence of P-56. A normal landing ensues.

Narrative: We were cleared for the River Visual to Runway 19 after sequence vectors off the FRDMM 3 Arrival. We intercepted the river north of the Georgetown Reservoir and checked in with DCA Tower. We were given 'Cleared to land 19.' followed shortly by 'slow to final approach speed.' We complied while following the river. As we approached the Key Bridge; Tower requested we 'square the corner to final.' We quickly confirmed that we could not come left in order to square the corner due to area P-56. We continued our ground track so as to [not] violate P-56. We had no conflict with departing traffic and had an uneventful landing.In a pilot's mind; 'square the corner to final' means turn to 90 degrees off final; then make one 90 degree turn to line up on final. In this case; when given the request by Tower (and without superior situational awareness) we could have turned directly into P-56. I recommend that Tower use 'square the turn to final' only on Runway 1. Also; list a warning on Company DCA Safety alert page detailing this possibility by the Tower.

Data retrieved from NASA's ASRS site 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	1382794
Time
Date	201608
Local Time Of Day	0601-1200
Place
Locale Reference	DCA.Airport
State Reference	DC
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	Visual Approach
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 156
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Deviation - Procedural Clearance

While on the river visual to runway 19 at dca; a B737-700 captain is instructed to square his turn to final for spacing by the tower. He declines due to the presence of P-56. A normal landing ensues.