A captain described the complexity of complying with an ATC airspeed and altitude constraint change ...

Narrative:

We began our descent into mem on the LTOWN6 RNAV arrival. We were first cleared down to an altitude of FL230 shortly after bwg without a crossing restriction at a specific fix. Soon thereafter we were given 'descend via the LTOWN6 arrival landing south; except maintain 310 knots.' our next amended clearance was 'descend via the LTOWN6 arrival except maintain 310 knots and cross axxel at or below FL200.' this contradicted the (small and very easy to miss) 'a' labeled speed and altitude restrictions at axxel. After axxel; we were told to 'resume published and descend via the arrival speed.' we then had a short discussion of what published speed we were expected to be flying at that point. While all of this is going on; we were then trying to follow the very confusing approach plate and nearly overlooked the speed restriction at copen. While we met all of the restrictions of the arrival; we felt extremely behind on the arrival due to all of the changes to the already complex arrival chart. Every flight that we heard on this arrival was getting similar changes to their speed and altitude restrictions. This particular arrival is very confusing on paper. While the chart reads left-to-right; the flight path is from right-to-left. The point at which the chart transitions to the next frame is a very critical point of the arrival. That transition combined with three fixes; wlder; ltown; and copen; that are only 4NM (that is labeled by a 'B') and 2NM apart; makes this a death-trap for crews. The restrictions at casot; axxel; and kelne have no business being labeled with an 'a' as it is very easy to miss. This complex presentation of the arrival is exacerbated by ATC changing speed and altitude restrictions. This chart needs to be a fold-out chart. The two-frame presentation makes this chart a disaster. The procedure itself could also use some work. Under no circumstances should fixes on an arrival be that close together where you are left with 3 fixes within 6NM of each other. Lastly; if ATC is going to issue an arrival; they should not change the restrictions of that arrival on a regular basis. Looking back at the events; I should have refused to 'descend via' after our restrictions were changed for the third time. However; we did not feel as if we were behind until we were about wlder when we were both heads-down trying to make heads or tails of the arrival plate.

Original NASA ASRS Text

Title: A Captain described the complexity of complying with an ATC airspeed and altitude constraint change on the already complex MEM LTOWN 6 RNAV procedure.

Narrative: We began our descent into MEM on the LTOWN6 RNAV Arrival. We were first cleared down to an altitude of FL230 shortly after BWG without a crossing restriction at a specific fix. Soon thereafter we were given 'descend via the LTOWN6 arrival landing south; except maintain 310 knots.' Our next amended clearance was 'descend via the LTOWN6 arrival except maintain 310 knots and cross AXXEL at or below FL200.' This contradicted the (small and very easy to miss) 'A' labeled speed and altitude restrictions at AXXEL. After AXXEL; we were told to 'resume published and descend via the arrival speed.' We then had a short discussion of what published speed we were expected to be flying at that point. While all of this is going on; we were then trying to follow the very confusing approach plate and nearly overlooked the speed restriction at COPEN. While we met all of the restrictions of the arrival; we felt extremely behind on the arrival due to all of the changes to the already complex arrival chart. Every flight that we heard on this arrival was getting similar changes to their speed and altitude restrictions. This particular arrival is very confusing on paper. While the chart reads left-to-right; the flight path is from right-to-left. The point at which the chart transitions to the next frame is a very critical point of the arrival. That transition combined with three fixes; WLDER; LTOWN; and COPEN; that are only 4NM (that is labeled by a 'B') and 2NM apart; makes this a death-trap for crews. The restrictions at CASOT; AXXEL; and KELNE have no business being labeled with an 'A' as it is very easy to miss. This complex presentation of the arrival is exacerbated by ATC changing speed and altitude restrictions. This chart needs to be a fold-out chart. The two-frame presentation makes this chart a disaster. The procedure itself could also use some work. Under no circumstances should fixes on an arrival be that close together where you are left with 3 fixes within 6NM of each other. Lastly; if ATC is going to issue an arrival; they should not change the restrictions of that arrival on a regular basis. Looking back at the events; I should have refused to 'descend via' after our restrictions were changed for the third time. However; we did not feel as if we were behind until we were about WLDER when we were both heads-down trying to make heads or tails of the arrival plate.

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	1093883
Time
Date	201306
Local Time Of Day	0601-1200
Place
Locale Reference	M03.TRACON
State Reference	TN
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Medium Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR LTOWN 6 RNAV
Flight Plan	IFR
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance

A captain described the complexity of complying with an ATC airspeed and altitude constraint change on the already complex mem ltown 6 RNAV procedure.