Dan Potter

According to the accounts of numerous witnesses on the ground near the World Trade Center, military fighter jets are first noticed flying over Manhattan either shortly before or soon after the second collapse, at 10:28 a.m. Some witnesses recall fighters arriving just before this collapse:
Emergency medical technicians Dulce McCorvey and Michael D’Angelo hear fighters flying over Manhattan at unspecified times after the first tower’s collapse. [City of New York, 10/3/2001; City of New York, 10/24/2001]
Fire Lieutenant Sean O’Malley and firefighters Pete Giudetti and Dan Potter notice jet fighters flying overhead soon before the second collapse. [City of New York, 10/12/2001; City of New York, 12/6/2001; Smith, 2002, pp. 49-50]
Other witnesses say the fighters arrive soon after this collapse:
Deputy Fire Chief Robert Browne, police officer Peter Moog, and emergency medical technicians Richard Zarrillo and Jason Katz notice fighters overhead immediately after, or fairly soon after, the second tower’s collapse. [City of New York, 10/24/2001; City of New York, 10/25/2001; City of New York, 12/20/2001; Fink and Mathias, 2002, pp. 79-80]
Mayor Rudolph Giuliani, Police Commissioner Bernard Kerik, and Office of Emergency Management Director Richard Sheirer are heading north together after leaving their temporary command post on Barclay Street (see (9:50 a.m.-10:10 a.m.) September 11, 2001). In some accounts, all three of them recollect hearing the first military jets overhead soon after the second tower’s collapse. [Kerik, 2001, pp. 339-340; Giuliani, 2002, pp. 14; 9/11 Commission, 5/18/2004 ] However, according to another account, Giuliani hears the first jet slightly earlier, at around 10:20 a.m. And, in his private testimony before the 9/11 Commission, Kerik claims to have heard a fighter jet coming when he was heading to the temporary command post on Barclay Street, i.e. shortly before 9:50 a.m. [Barrett and Collins, 2006, pp. 348-349]
A few witnesses claim the fighters arrive earlier on, before the first collapse at 9:59 a.m.:
Emergency medical technician Frank Puma and Port Authority Freedom of Information Administrator Cathy Pavelec say they see fighter jets overhead at unspecified times before the first collapse. [City of New York, 12/12/2001; Fink and Mathias, 2002, pp. 68]
The fighter(s) are presumably the F-15s launched from Otis Air Force Base at 8:46 a.m. (see 8:46 a.m. September 11, 2001). However, the 9/11 Commission will claim that these arrived over Manhattan at 9:25 a.m. (see 9:25 a.m. September 11, 2001), which is significantly earlier than most of the witnesses on the ground recall.