Patient safety is at risk because of increasing GP workloads in the UK, doctors' leaders are warning.
The Royal College of GPs said the pressure of more consultations, complex cases and increased bureaucracy was causing fatigue and burnout.
The RCGP said such difficulties would not be allowed to happen with pilots or train drivers.
It also called for a new system of distress signals so practices under extreme pressure could raise the alarm.
That would be similar to the red and black alerts hospitals use when they have surges of patients.
The alerts act as a warning to the rest of the system to relieve pressure where possible by taking on their patients or not referring new cases to them.
In extreme cases hospitals can even close their doors to new patients - although the RCGP is not suggesting this happens in general practice.
The college also said mandatory breaks should be introduced to minimise the risk of mistakes.
To make the case, the RCGP has produced a consultation paper highlighting the pressures GPs are under.
Consultations have risen by nearly a fifth in the past five years, to more than 360 million a year, far outstripping the rise in GP numbers that has been seen.
It means there are now fewer GPs per person than there were in 2009, with the RCGP saying another 3,300 GPs are needed.
While many of the figures in the report relate to England, the RCGP said it was a UK-wide problem.
Dr Maureen Baker, who chairs the RCGP, said the problem needed addressing urgently, with waiting times getting worse and GPs having to work 11- and 12-hour days, which increased the risk of mistakes, such as medication errors.
"Few of us would voluntarily board a plane flown by a visibly tired pilot or get on a train where we knew the driver had spent too much time at the controls - yet there are no methods or systems for addressing doctor and staff fatigue in general practice," she said.
"Our intention is not to panic patients but to send out a pre-emptive strike to ensure that we take steps now to protect patients from the risks arising from doctor and staff fatigue."
Health Secretary Jeremy Hunt set out plans last month to invest in general practice.
He promised extra investment, including the recruitment of 5,000 new GP and another 5,000 support staff, including practice nurses, during the Parliament.
The idea of creating financial incentives for those willing to work in the most deprived areas was also put forward.
But, crucially, he linked it to the profession embracing seven-day working, to the anger of the British Medical Association.
A spokesman from the Department of Health said: "GPs do a fantastic job and we know they are under pressure as our population ages and more people live with long-term conditions. That's why we have committed to make 10,000 more staff available for general practice."