Medium Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Distraction; Confusion; Situational Awareness; Workload; Time Pressure
ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance
Flight Crew FLC complied w / Automation / Advisory; Flight Crew Returned To Clearance
Chart Or Publication; Procedure
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.
A Captain described the complexity of complying with an ATC airspeed and altitude constraint change on the already complex MEM LTOWN 6 RNAV procedure.