There have been a lot of references to AF 447, many implying that oil slicks or debris was found quickly. Conversely, BEA reported at least 5 days between loss of aircraft and first sightings.
FLIGHT AF 447
http://www.bea.aero/en/enquetes/flig...e.wreckage.pdf
"During the morning of 1st June, extensive air and naval resources were mobilized to find
any trace of the aeroplane and possible survivors. In spite of this, it was not until 5 days
later, and on the following days, that human remains and floating debris were found on the
surface of the sea, north of the last position transmitted automatically by the aeroplane."
"The discovery of the first floating debris at the surface of the sea, about 70 km north of the
last known position did not, however, make it possible to determine the point of impact,
due to a lack of precise knowledge of the currents that made the debris drift from the time
of the accident."
http://www.bea.aero/docspa/2009/f-cp...p090601.en.pdf
"On Sunday 31 May 2009, . . . flight AF 447 . . . departure was planned for 22 h 00. . . . The French and Brazilian navies found debris belonging to the aeroplane from 6 June onwards. . . . The wreckage was localised on 2 April 2011 during the fourth phase of the sea searches. . . . The aeroplane wreckage was found about 6.5 NM on the radial 019 from the last known position, slightly to the left of the planned route."
"The first search phase aimed at detecting and locating the acoustic signals transmitted by the Underwater Locator Beacon (ULB) fitted on each flight recorder. As a priority, the aeroplane’s planned flight path as well as the greatest possible area inside the 40 NM circle was swept by two Towed Pinger Locators (TPL).
No signal from either of the beacons was detected by the sensors deployed in the area despite TPL passing by, on two occasions, not far from the debris field, on 22 and 23 June 2009. "