US airlines' revenue trends improve in October

* Industry mainline RASM falls 14 pct- analyst

* October typically a busy month for business travel

* Seven of nine largest airlines cut capacity in Oct

NEW YORK, Nov 6 (Reuters) - Traffic for the top three U.S. airlines slumped in October, but load factors for most of the nine largest carriers rose and the decline in unit revenue showed signs of slowing down.

Delta Air Lines' (DAL.N: Quote, Profile, Research) traffic fell 6.5 percent in October versus a year ago. The world's largest carrier said its load factor, a measure of how full a plane is, rose 1.6 points to 84.2 percent.

No. 2 airline AMR Corp's (AMR.N: Quote, Profile, Research) American Airlines and no. 3 carrier UAL Corp's (UAUA.O: Quote, Profile, Research) United Airlines also reported traffic declines last month.

An FTN Equity Capital Markets analyst said Friday that unit revenue, a measure of profitability, did not fall as sharply in October as it did the prior month, a sign that operating conditions may be improving.

"October unit revenue improved sequentially from the prior month," analyst Michael Derchin said in a note. "It now appears that June and September marked the double bottom for the airlines in this important earnings driver."

U.S. Airways (LCC.N: Quote, Profile, Research) said its consolidated unit revenue sank 10 percent in October, better than the 15-percent decline it logged in September.