And there was one clear way he could be certain of foiling the enemy's plans.
The admiral reached for a telephone with an outside line. He wouldn't like being awakened, either, but there was no way of helping that.
"Captain!" the sonar officer called out. "Splashes ahead and to port!"
"Very well." Commander Fareed Asefi was not worried. "They are ours."
Noor was one of Iran's six Tareq-class submarines— what the West called Kilos. Noor, hull number 902, had been acquired from a cash-desperate Russia in 1993, the second of an initial purchase of three diesel-electric submersibles. Like other Kilo-class vessels, she was 74.3 meters long, displaced just over three thousand tons, and was operated by a crew of fifty-three— fifty-four if you counted the mullah Reza Sharabiani.
A moment later a sharp, ringing ping sounded through Noor's control room. Sharabiani started, looking upward. "What is that?"
Asefi smiled. "Active sonar. One of our aircraft is overhead, dropping sonobuoys. These are devices that float on the surface of the water, sending out active sonar pulses. The pulses are like radar. They reflect off of ships and submarines, are picked up by the buoy, and transmitted back up to the aircraft."
"And you say it is one of ours?"
"Assuredly, Mullah. We are well within Iranian territorial waters here. Our ASW forces are joining in the hunt for the American submarine."
"Active sonar pulses, Captain," the sonar officer announced, confirming Asefi's guess. "Iranian origin. Bearing zero-eight-one."
"Ah." Sharabiani stroked his beard, relaxing. "Then we can be sure the enemy will soon be cornered and brought to the surface. Ah… how do our pilots know that the signals picked up by their sonobuoy are from a friendly submarine, and not from the enemy?"
In fact, Asefi had just been considering that point. True, a Tareq-class sub was almost one hundred meters shorter than the Ohio. It would take a skilled sonar operator to judge target size from a series of reflected pings. Fortunately, headquarters would have put their best ASW personnel into the air for this operation.
"Captain! Torpedo in the water!"
"What?" Or perhaps not.
"Torpedo in the water, bearing zero-five-five! It has acquired! Torpedo has gone active!"
Which meant an Iranian antisubmarine torpedo was now homing on the Noor.
"Range!" With active sonar in the water, from the sonobuoy and from the torpedo itself, it was possible for Noor's sonar officer to calculate the torpedo's range.
"Sir! Twenty-eight hundred meters!"
"Maneuvering! Come hard to starboard! Make course… two-three-five! All ahead full!"
Calculations flitted through his mind, relentless and unforgiving. For air-launched ASW work, Iran used Mark 46 light torpedoes, weapons originally acquired decades ago from the United States. The Mk. 46 had a range of eight thousand meters and could travel at 45 knots. At her best, Noor could manage seventeen knots.
At 45 knots, the torpedo would cover 2.8 kilometers in just under two minutes. In that same time, Noor, running directly away from the incoming weapon, would cover about three-tenths of a nautical mile, or half a kilometer. The Mark 46 would cover that additional distance in another twenty or thirty seconds. Make it… make it…
"Torpedo impact in one minute, twenty seconds!" the sonar officer reported, beating by a hair Asefi's own calculations. Less than he'd been thinking… but then, Noor would need precious time to accelerate to a full seventeen knots, and more time still to complete her turn away from the torpedo.
"This is madness!" Sharabiani cried. "Raise them on the radio! Tell them they've fired on one of their own!"
"It's not that simple, Mullah." In fact, unlike a wire-guided torpedo from another submarine, the Mk. 46, once fired, could not be recalled or disabled. "I wish it were."
"Torpedo now at twelve hundred meters," Lieutenant Mohammadi, the sonar officer, reported. The man sounded impossibly calm, almost bored. "Time to impact, fifty seconds."
"But they are firing on their own submarine!"
"I know, Mullah. Friendly fire. It is one of the dangers of warfare."
The mullah's face had gone death-white. His beard wagged up and down as he mouthed a fervent, desperate prayer.
Fareed Asefi joined him, silently. Allah, the merciful and the most wise! If it be your will, save us!.. The captain of the Noor was absolutely convinced in the rightness of the Shi'ite Islamic cause, and of the power of almighty God. He was realist enough to know, however, that fatal accidents did happen in war, no matter how just and holy your cause.
"Diving Officer! What is our depth?"
"Sir! Depth twenty-eight meters!"
Deep, for these waters.
"What is the depth beneath our keel?"
"Sir! Depth beneath keel, fifteen meters!"
There was no hope of finding a thermocline beneath which they could hide from the approaching weapon's sonar. Sometimes you could find a thermocline out in the main channel, where the water was as much as sixty meters deep. But not here, in these shallows.
"Range seven hundred meters," Mohammadi announced. "Time to impact, thirty seconds."
"Release countermeasures!" Asefi snapped. Either God would deliver them in the next few moments, or He would not. There was yet a human trick or two, however, that Asefi knew he could use to improve the chances of divine intervention.
A pair of cylinders dropped from the Noor's flanks, swiftly falling astern. Moments after release they began filling the water around them with a dense cloud of bubbles, created by the interaction of seawater and the chemicals they carried. With luck, the torpedo's active sonar would reflect from the bubbles, breaking its lock on the Noor.
"Maneuvering! Come hard right, twenty degrees!" Asefi ordered. It would help if, when the torpedo punched through the decoy bubble cloud, Noor were no longer directly ahead of it. Once the torpedo lost its target, it was programmed to begin circling, sending out active pings in quest of a target. The idea was to turn away from it and try to get outside of its reach. After traveling eight kilometers, the torpedo would exhaust its fuel supply.
"I have lost the torpedo, Captain," Mohammadi announced. Several men let loose a cheer.
"Silence!" Asefi yelled. "We're not out of this yet!" Sonar had lost the incoming target behind the bubbles, but it would emerge any moment now….
"I have the torpedo again, Captain," Mohammadi reported. "Torpedo is now circling… torpedo has re-acquired."
Someone in the control room groaned aloud. Asefi did not bother to reprimand him. The countermeasure ploy had failed.
"Range now four hundred meters," Mohammadi said, an emotionlessly recited death sentence. "Time to impact… twenty seconds."
Sharabiani let loose a wail of despair, dropped to his knees and began praying aloud.
"Diving Officer!" Asefi yelled. "Blow all ballast! Up planes! Emergency surface! Surface!"
The deck tilted sharply, bow rising, and Asefi heard the sharp and boiling hiss of seawater being blasted from Noor's ballast tanks by high-pressure air.
There was just a chance that the sudden maneuver would outfox the simple-minded torpedo bearing down on them. Besides, if the Noor were about to be hit by a warhead consisting of forty-three kilograms of PBXN-103 high explosives, he would buy precious time for the crew if they were hit on the surface, rather than fifty meters down.