LONDON, May 31 (Reuters) - The number of idle commercial aircraft has been rising since the September 11 attacks, which cut demand for air transport and left airlines with too many planes. These unemployed aircraft are a threat to the production lines of Boeing Co (BA) and Airbus SAS, the main business unit of Franco-German aerospace group EADS (EAD)(EAD). But analysts disagree over how many of these planes will return to service. An accompanying report, "ANALYSIS-EADS, Boeing hope idle planes stay idle" [nL31480827] discusses the issues. Jet commercial aircraft parked: April May Change Fleet^ Pct parked Airbus A300* 52 49 -3 428 11.4 A310 26 26 244 10.7 A319 19 19 433 4.4 A320 50 50 1,043 4.8 A321 17 19 2 236 8.1 A330 25 22 -3 217 10.1 A340 17 17 216 7.9 Boeing 707* 50 51 1 296 17.2 717 23 25 2 98 25.5 727* 417 444 27 1,190 37.3 737 JT8D* 240 237 -3 884 26.8 737 CFM 112 116 4 3,076 3.8 747* 138 138 1,103 12.5 757 48 44 -4 1,004 4.4 767 49 52 3 863 6.0 777 3 2 -1 400 0.5 Douglas DC-8* 79 79 228 34.6 DC-9* 168 182 14 698 26.1 DC-10* 113 114 1 378 30.2 MD-80 99 95 -4 1,170 8.1 MD-90 10 10 115 8.7 MD-11 14 13 -1 195 6.7 Other, regional jets 297 341 44 2,210 15.4 Total or average 2,066 2,145 79 16,725 12.8 Source: Airclaims via J P Morgan. * Aircraft whose technology is all from the early 1970s or earlier. The 747 total includes a handful of 1980s-technology 747-400s. ^ Active and idle aircraft. ©2002 Reuters Limited.