Although the current military and civilian policy with regard to aircraft crashes is to remove all trace of the wreckage, regardless of the remoteness or inaccessibility of the location (presumably because of environmental and security concerns, and to investigate the causes of the accident), here is a list of recent crashes (since 1970) at remote locations in the Scottish mountains (and elsewhere).
Military:
RAF Hunter, near Blair Atholl (Beinn a'Ghlo/Carn Liath?), 1970:
http://www.ukserials.com/losses-1970.htm
RAF Harrier near Kyle of Lochalsh, 1972:
http://aviation-safety.net/wikibase/wiki.php?id=55585
USAF F-111, near King's Seat, Fife, 1972:
http://www.raf-upper-heyford.org/Mishaps.html
RAF Jaguar near summit of Ben Lui, 1979:
http://www.incallander.co.uk/rescue.htm
http://heavywhalley.wordpress.com/2012/07/22/the-jaguar-crash-on-ben-lui-november-1979/
http://www.alpinejournal.org.uk/Contents/Contents_2002_files/AJ%202002%20230-236%20Card%20Pibworth.pdf
USAF RF-4C Phantom, on Cairnsmore of Fleet, 1979:
http://www.peakdistrictaircrashes.co.uk/pages/scotland/scotland68-0566.htm
USAF F-111 on Craignaw near Merrick, 1979:
http://en.wikipedia.org/wiki/Craignaw
RAF Hunter, Cullins, Skye, 1980
MOD Accident Summary
USAF F-111 on Sgurr na Stri, Skye, 1982:
http://www.isbuc.co.uk/People/F-111Crew.htm
http://www.bbc.co.uk/news/uk-scotland-highlands-islands-20663807
RAF SAR Wessex on Ben More (Crianlarich), 1987:
https://heavywhalley.wordpress.com/2017/02/01/30-years-ago-was-the-wessex-helicopter-crash-on-ben-more-and-the-tragic-loss-of-harry-lawrie-killin-mountain-rescue-team-leader/
http://www.aircrashsites-scotland.co.uk/wessex_ben-more.htm
RAF SAR Sea King in Coire Ardair, Creag Meagaidh, 1989:
MOD Accident Summary
http://www.aircrashsites-scotland.co.uk/sea-king_craig-meagaidh.htm
RAF Shackleton, Maodal, Isle of Harris, 1990
http://www.stornowaygazette.co.uk/news-features/Stories-that-made-the-headlines.2072112.jp
MOD Accident Summary
RAF Hercules at Glen Loch near Beinn a'Ghlo, 1993:
http://aviation-safety.net/database/record.php?id=19930527-0&lang=en
http://www.baaa-acro.com/photos/C130-RAF-Blair%20Athol.jpg
MOD Accident Summary
RAF Chinook, Mull of Kintyre, 1994 (not a mountainous area, but included here for completeness as this was a very high-profile crash):
http://en.wikipedia.org/wiki/Chinook_crash_on_Mull_of_Kintyre
RAF Tornado in Glen Ogle, 1994:
http://www.robroyway.com/interest.html#chapter9
MOD Accident Summary
http://www.peakdistrictaircrashes.co.uk/pages/scotland/scotlandzg708.htm
RAF Jaguar, Lochmaben, 2000:
http://news.bbc.co.uk/1/hi/scotland/1693469.stm
MOD Accident Summary
Two USAF F15s on Ben Macdui, 2001:
http://news.bbc.co.uk/1/hi/scotland/4686602.stm
Article about the environmental impact of the crash site
RAF SAR Sea King stranded at Coire an t-Sneachda, Cairngorms, 2006 (not strictly a crash!):
http://news.bbc.co.uk/1/hi/scotland/highlands_and_islands/6332159.stm
RAF Tornado, Glen Kinglass, 2009
http://news.bbc.co.uk/1/hi/scotland/glasgow_and_west/8130528.stm
RN SAR Sea King emergency landing in Glencoe, 2013 (not strictly a crash!):
http://www.bbc.co.uk/news/uk-scotland-highlands-islands-24607718
Civilian:
Vickers Viscount crash on Ben More (Crianlarich), 1973:
http://www.aircrashsites-scotland.co.uk/viscount_ben-more.htm
http://aviation-safety.net/database/record.php?id=19730119-2
http://heavywhalley.wordpress.com/2012/07/19/my-early-days-at-kinloss-ben-more-viscount-crash-at-crainlarich-tragedy-on-tower-ridge-ben-nevis/
Bell 206 Jet Ranger helicopter crash on Loch Avon, Cairngorms, 1977 (crashed in January on the frozen surface of the loch, which held the weight of the helicopter on a thickness of 1 metre of ice, allowing the pilot and passenger to survive the crash and be rescued that night in temperatures of -12°C after walking along Strath Nethy; a short article about this was published in the Journal of Meteorology, volume 2, 1976-1977, number 18):
http://www.aaib.gov.uk/cms_resources.cfm?file=/1-1978%20G-BAYA.pdf
Light plane (Piper PA-28 Cherokee) crash on Ben Ledi, 1981:
http://www.incallander.co.uk/rescue.htm
Google News: Glasgow Herald article from Nov 18th 1981
Pan Am Boeing 747, Lockerbie, 1988 (not a mountainous area, but included here for completeness as this was a very high-profile crash):
http://en.wikipedia.org/wiki/Pan_Am_Flight_103
Light plane crash on Beinn an Leathaid, Ardnamurchan, 1989:
http://www.peakdistrictaircrashes.co.uk/pages/scotland/scotlandei-bgk.htm
Light plane (Cessna 210 Centurion) crash, Campsie Fells, 1990:
http://www.aircrashsites-scotland.co.uk/cessna-210_dunbrach-hill.htm
Light plane (Grob G115) crash on Loch Muick, Lochngar, 1992
http://www.aaib.gov.uk/cms_resources.cfm?file=/Grob%20G115,%20G-BPKG%2008-92.pdf
http://www.heraldscotland.com/sport/spl/aberdeen/bang-heard-by-balmoral-maid-before-plane-crash-1.747321
Light plane crash in Glen Lyon, 2000:
http://news.bbc.co.uk/1/hi/scotland/1048735.stm
Light plane crash on Mullach an Rathain, Liathach, Torridon, 2000:
http://news.bbc.co.uk/1/hi/scotland/1187972.stm
http://news.bbc.co.uk/1/hi/scotland/1422974.stm
Light plane crash on Lochnagar 2001:
http://news.bbc.co.uk/1/hi/scotland/1137196.stm
http://news.bbc.co.uk/1/hi/scotland/1136774.stm
Light plane crash on Seana Bhraigh, 2004:
http://news.bbc.co.uk/1/hi/scotland/3946537.stm
Light plane crash on Mount Keen, 2005:
http://news.bbc.co.uk/1/hi/scotland/4141388.stm
http://www.gairney.plus.com/Aircraft/Photographs/aircraft_Wrecks/aircraft-HGW-3.htm
Glider crash on Beinn a'Bhuird, 2006:
http://news.bbc.co.uk/1/hi/scotland/north_east/5167612.stm
Light plane crash near Loch Scammadale and Carn Dearg, 2007:
http://news.bbc.co.uk/1/hi/scotland/glasgow_and_west/6543373.stm
Light plane crash on Cairn Gorm, 2008:
http://news.bbc.co.uk/1/hi/scotland/highlands_and_islands/7332901.stm
Microlight aircraft crash on Ben More (Crianlarich), 2012:
http://www.bbc.co.uk/news/uk-scotland-tayside-central-20963442
Light plane (Piper Cherokee) crash in Glen Kinglass, 2015:
http://www.bbc.co.uk/news/uk-scotland-glasgow-west-32187183
Light plane crash near Beinn Lora, 2016:
http://www.bbc.co.uk/news/uk-scotland-glasgow-west-36954381