News headlines: 'Killer in the cockpit'
The most shocking story of the day is the one that dominates Friday's papers: the discovery that the Germanwings Airbus A320 which crashed on Tuesday was probably deliberately flown into a mountain by its co-pilot.
The media's attention is now focused on Andreas Lubitz, the 28-year-old German who was second-in-command of the doomed jet, and who died along with the other 149 people on board.
The Independent says acquaintances and neighbours of Lubitz say the "most shocking thing" about the man, now effectively suspected of being a mass murderer, was "he appeared so totally normal".
A friend from a gliding club he belonged to tells the paper: "I'm just speechless. I don't have any explanation for this. Knowing Andreas, this is just inconceivable for me. He had a lot of friends; he wasn't a loner."
The Times explores the more troubled side of Lubitz's psyche.
The paper says as a 21-year-old he had needed treatment for severe depression, and this caused him to be suspended from a Lufthansa pilot training course.
It adds sources say he had a breakdown at the time. He qualified as a pilot in 2013, joining Lufthansa's budget operation Germanwings.
Psychologist Dr Jennifer Wild says that while suicidal people rarely harm others, "people make bad decisions when they are severely depressed.
"If Lubitz was depressed he would have suffered from irrational thinking."
The Daily Mail's front cover asks, "Why earth was [Lubitz] allowed to fly?"
The paper says airline bosses were aware of the junior officer's history of depression.
It adds that reports from Germany suggest that Lubitz was "struggling to cope" with a relationship break-up, and police searching his flat in Duesseldorf have made a "significant discovery". The paper adds that sources insist the item found was not a suicide note.
The Mail also turns its attention to technology, asking why technology to take control of planes remotely from the ground is not fitted to passenger jets.
"Anti-hijack systems" were being developed by Boeing in the wake of the 9/11 attacks, the paper continues, but support for their use has stalled over fears planes could be taken over by hackers.
"Unions representing pilots are also against the move," it adds.
The Times says a £62m consortium led by Britain's BAE are pioneering "sense and avoid" technology to provide pilotless planes.
It says 500-mile test flights have taken place entirely without pilots between sites in Lancashire and Scotland. A trained pilot was on board in case of an emergency, but the autopiloted plane performed perfectly.
Aviation author Giles Whittell, who writes the analysis, says it is predicted that all cargo flights will be pilotless by 2035, but passenger planes could remain "human controlled".
It might not have been the televisual event that the final series of Downton Abbey is widely predicted to be in the press, but the Cameron-Milliband pre-election "grilling" attracts much press comment.
The party leaders were interviewed separately by Jeremy Paxman and answered questions from a studio audience moderated by Kay Burley.
Referring to the robust interrogation from the former BBC Newsnight presenter, few media outlets can resist punning that the party leaders were "stuffed by Paxo".
Who "won" the Channel4/Sky programme depends on which political hue of paper you read.
The Daily Telegraph says a snap ICM poll suggested that 54% of people thought the Conservative leader came out top from the encounter.
However a panel of five of the paper's own "experts" seem to put Mr Miliband ahead by 3-1, with Tim Stanley voting for Jeremy Paxman as "winner".
The Telegraph's sketch-writer Michael Deacon said that although Paxman "was... still doing the despairing headmaster routine - withering glances, long-suffering sighs, hand clamped to the side of his face" he "allowed Mr Cameron to get away with flabby, evasive answers".
Ed Miliband he said by contrast, "was earnest, wide-eyed, with occasional bursts of self-deprecating joviality". And two jokes about that bacon sandwich picture.
Kevin Maguire in the Daily Mirror was never going to be kind to the prime minister and in his verdict Mr Cameron looked "as uncomfortable as Dustin Hoffman having his teeth pulled in Marathon Man".
"Jeremy Paxman was merciless exposing the failures and broken promises of the five wasted years," he adds.
The Times's leader comment is more ambivalent, saying "David Cameron gave a defensive account of a good case. Ed Miliband gave a good account of a weak one".
The paper says the Labour leader's performance in the interview was "the inverse of Mr Cameron's" in that he avoided his party's past record, but had a "polished if rather abstract account" of his vision for the future.
But it adds: "On the critical question... of whether Labour borrowed and spent too much, Mr Miliband stuttered his way to the wrong answer," it claims.
The publication of 27 letters written by Prince Charles to various government departments can go ahead following a prolonged legal battle.
The Guardian, which brought the case to reveal the contents of the so-called "black spider letters" (named after the prince's spindly handwriting), hails the victory of its campaign, which began with a Freedom of Information request 10 years ago.
The paper explains that parts of the letters may still be redacted over privacy concerns, and no timetable has yet been established over their release.
"The letters are between Charles and ministers in seven Whitehall departments, including those responsible for health, farming, and planning - all areas where Charles has previously lobbied politicians on controversial issues, such as the availability of complementary medicine through the NHS, organic farming and architecture. They were sent in 2004 and 2005," it continues.
In its analysis of the battle over the letters, the Guardian's Robert Booth writes: "The forthcoming publication of the prince's letters will be a watershed in his preparation for the throne - and the acid test of his public popularity.
"It has become clear that the 66-year-old heir wants to rule in a far more outspoken way than the taciturn Queen."
In the Daily Mirror, pro- and anti- letter release arguments are made by Graham Smith, of the anti-monarchist organisation Republic, and Ingrid Seward, of the staunchly royalist Majesty magazine.
"Is Charles meddling or not? We have a right to know," says Mr Smith.
"Anyone should be able to write a personal letter without the risk of thinking it's going to become public property," counters Ms Seward.
Columnist Philip Collins in the Times says Charles "wants power without responsibility".
"In a transparent time, secrecy will be the enemy of monarchy," he adds.
"Charles is already jeopardising the compact that his mother made with the nation."
The Independent's opinion column agrees.
"Prince Charles's meddling has already weakened his reputation; his resisting of openness threatens more serious damage to the monarchy," it claims.
Cartoonist Matt in the Daily Telegraph ties up the story with the recent re-interment of King Richard III.
Picturing the medieval monarch facing flying arrows and general mayhem at Bosworth Field, Matt has the king say: "I shall be writing one of my letters about this..."
Who says the papers never give you any good advice? In Friday's Daily Telegraph you learn how maths can teach you when is the best time to find your ideal life partner.
It says a new book, The Mathematics of Love, by University College, London academic Dr Hannah Fry attempts to quantify nature's chemistry.
Dr Fry says her research suggests no one is likely to find that special someone in the first 37% of their "dating life".
The paper says this means that someone who could be dating between the ages of 15 and 40 should not settle down with anyone they meet before they are 24.
Among her other tips, the paper continues, are finding slightly less attractive friends to hang around with.
"No one cares if you look like Brad Pitt or Angelina Jolie. All they care about is how you look compared to everyone else," she tells the Telegraph.
The latest national gallery to open will perhaps be of more significance to those in Dr Fry's "non settling down years" than to older Britons.
The Independent reports on the new National Videogame Arcade in Nottingham, a museum it says, that "marks the point where the likes of Super Mario come in from the cultural cold."
One of the founding fathers of the UK's £3.9bn gaming industry Ian Livingstone tells the paper, "Other entertainment media have their cultural centres, the National Theatre and the National Film Theatre and all that, celebrated in permanent locations.
"I think it's important to have one for games too because it's gone beyond entertainment. It is mainstream culture and has an impact on society, economic impact and is a learning tool. "
As well as encountering the latest technology, visitors can experience the vintage gaming experience of such pre-historic computers as the BBC Micro and ZX Spectrum.
There is an even a copy of a famous "lost" Atari game ET, which was recently found buried in the New Mexican desert, the Independent adds.
And finally, who can resist a picture of the world's smallest dog?
You won't find it here - we don't have the rights - but the Daily Express pictures the two-and-three-quarter inch Chihuahua Toudi in the palm of her owner's hand.
Toudi weighs just 10-and-a-half ounces and her Polish owners say they are having to be very careful. She is the same colour as their floor.
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