Every now and then Iran's American-made Phantom jet fighters scramble into the air to check out reports of "alien helicopters" being spotted in some part of the country.
A few nights ago, Tehran's sleeping residents were startled awake by the roar of the Phantoms over the city, crisscrossing the sky near the United States Embassy.
Air Force chief Maj. Gen. Amir Bahman Bagheri explained later that "flying objects" similar to helicopters had been spotted on the radar screens, and the jets had been sent out to investigate.
They found nothing, of course.
On May 14, moreover, President Abolhassan Bani-Sadr said he had received information from sources in the United States that Washington had sent 96 US agents into Iran to launch a sabotage campaign. The US categorically denied the report, and there has been no further word about the saboteurs at this writing.
Some days ago, rumors flew through the northeastern Khorramshahr Province that eight helicopters had been seen over that province and also over nearby Isfahan Province. Again the planes returned to report a false alarm, and Maj. Gen. Hadi Shadmehr of the Joint Chiefs of Staff issued a statement to calm the public's concern.
Between the two false alarms, a group of 30 pasdars (revolutionary guards) searching the lowhills southeast of Tehran, discovered "another secret landing strip" only 60 kilometers (36 miles) from Tehran, on the edge of the Kavir Desert.
The pasdars said there were signs that the landing strip, fenced off with barbed wire as a "no-hunting zone," had been used recently by a number of helicopters.
Suspicious even in the best of times, the pasdars wanted to know why the gendarmerie and other military authorities had denied that any helicopters had flown in that area recently.
The pasdars, clearly hinting that there was a widespread pro-American element in the Iranian armed forces, had claimed earlier that the helicopters and aircraft used in the American hostage rescue bid on April 24, and 25 had actually been spotted by a number of radar stations on Iran's southern coast, but that the stations had not reported this to the central authorities.
The renewed suspicions about the armed forces also were apparent in the questions raised by such persons as Islamic judge Ayatollah Sadeq Khalkhali, about why the Sky Stallion helicopters abandoned by the American commandos in the Kavir Desert were bombarded by Iranian aircraft two days later before they could be thoroughly searched by the revolutionaries.
(In fact, there were ambiguous reports that one pasdar chief and two aides who got to the helicopters before the Iranian Phantoms did were killed.)
What has clearly shaken the revolutionary leaders in Tehran are revelations in the United States that the American commandos were to have been assisted in their rescue bid by pro-American Iranians.
The disclosures, which have been given wide publicity in Iran, were that the American commandos were to have hidden for a day in a mountain base somewhere to the north of Tehran and then moved into the city the next night in trucks provided by Iranians assisting them.
IT is no secret to Iranians (who are avid picnickers) that the former Shah had built an elaborate military base to the north of Tehran with a complex of barracks and other establishments dug into the mountains. There also are one or two above-ground bases in the area. None of these places is more than about 15 miles from the American Embassy -- a distance that could be covered in less than an hour.
But the strange "helicopter sightings" in Iran recently, mainly during the night hours, and the discovery of "another secret landing strip" near Tehran, with evidence that it had been used recently by helicopters, raises doubts about whether the commandos were to have stopped over for a day in the "mountain hideout" to the north of the city.
Whatever the truth of the matter, the Revolutionary Council appointed a three-man commission, soon after the April 24 and 25 bid, to investigate the whole question of connivance by a large number of Iranians in the attempt.
The commission, apparently led by Hojatolislam Akbar Hashemi Rafsanjani, a former student and aide of Ayatollah Ruhollah Khomeini, completed its work in a surprisingly short period of less than two weeks.
Hojatolislam Rafsanjani has submitted his report to the council, of which he is a member, and to Ayatollah Khomeini. So far there has been only a promise that the findings would be made known to the Iranian public.
It therefore is open to speculation whether the Rafsaniani report referred to the large number of Iranian civilians who have expressed regrets that the rescue mission failed.
Several, who make their pro-American feelings known only in private, have put the blame on President Carter. "He is an incompetent President," said one.
They would have liked to see the hostages freed, but some also have been secretly pleased to know that the commandos may have been aiming at toppling the regime itself. Such covert critics are sorry that this did not happen.
Meanwhile, the revolutionary leaders do no doubt for a minute that President Carter will try again, and the more strongly the American President denies it, the more they are convinced the "second bid" is coming.